Polycarbonate resin composition, method for producing same and molded article of this resin composition

ABSTRACT

To provide a polycarbonate resin composition excellent in the surface hardness, the heat resistance, the moldability and the flame retardancy. 
     A polycarbonate resin composition comprising at least a polycarbonate resin (a) and a polycarbonate resin (b) having structural units different from the polycarbonate resin (a), which satisfies the following requirements:
         (i) the pencil hardness of the polycarbonate resin (a) as specified by ISO 15184 is higher than the pencil hardness of the polycarbonate resin (b) as specified by ISO 15184;   (ii) the glass transition point Tg(a) of the polycarbonate resin (a) and the glass transition point Tg(b) of the polycarbonate resin (b) satisfy the relation of the following (Formula 1):       

         Tg ( b )−45° C.&lt; Tg ( a )&lt; Tg ( b )−10° C.  (Formula 1)
 
     and
         (iii) the pencil hardness of the polycarbonate resin composition as specified by ISO 15184 is higher by at least two ranks than the pencil hardness of the polycarbonate resin (b) as specified by ISO 15184.

TECHNICAL FIELD

The present invention relates to a polycarbonate resin composition and amethod for producing it, and a molded article of the resin composition.More particularly, it relates to a polycarbonate resin compositioncomprising at least two types of polycarbonate resins differing instructural units, and a method for producing it.

BACKGROUND ART

A polycarbonate resin is excellent in the mechanical strength, theelectrical properties, the transparency and the like, and is widely usedas an engineering plastic in various fields such as electric andelectronic equipment fields and automobile fields. In recent years, insuch application fields, reduction in thickness, downsizing and weightsaving of molded articles are in progress, and further improvement inthe performance of materials to be molded is required. However, aconventional polycarbonate resin made of bisphenol A as a raw materialhas not necessarily been sufficiently excellent in the surface hardness.Accordingly, development of a polycarbonate resin having a high surfacehardness has been desired, and several proposals have been made.

For example, Patent Documents 1 and 2 propose a method for producing apolycarbonate or a copolycarbonate excellent in the surface hardness byusing a bisphenol different from bisphenol A as a monomer. However, bythis method, even though a polycarbonate resin composition excellent inthe surface hardness is obtained, it is necessary to sacrifice otherphysical properties.

Further, Patent Document 3 proposes a method of bonding different typesof polymers on a molded specimen such as hard coating treatment, to forma multilayered structure. However, this method has such a problem thatthe shape of the molded article is limited to a sheet shape or the like,and the application is limited. Further, it has drawbacks of lowproductivity such that the number of steps increases so as to achieve amultilayered structure, a complicated treatment is required at the timeof molding, and defective articles are molded at the time of hardcoating.

Further, Patent Document 4 proposes to improve the surface hardness of ablended material of a polycarbonate resin derived from dimethylbisphenol cyclohexane and a bisphenol A type polycarbonate resin.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: JP-A-64-69625-   Patent Document 2: JP-A-8-183852-   Patent Document 3: JP-A-2010-188719-   Patent Document 4: WO2009/083933

DISCLOSURE OF INVENTION Technical Problem

With materials obtained by conventional methods, a polycarbonate resincomposition which has high strength even though it is thin, which hasexcellent heat resistance, moldability, flame retardancy and the like,which has a high surface hardness and which is excellent in the color,could not be obtained.

Under these circumstances, the object of the present invention is toprovide a polycarbonate resin composition being particularly excellentin the surface hardness and having excellent heat resistance,moldability (fluidity), color, impact resistance and flame retardancy.

Solution to Problem

The present inventors have conducted extensive studies to achieve theabove objects and as a result, they have found that a polycarbonateresin composition which attains the above objects can be achieved by apolycarbonate resin composition containing specific two types ofpolycarbonate resins, and accomplished the present invention.Specifically, it was found that a polycarbonate resin composition havingan excellent surface hardness and having excellent heat resistance,moldability, color and impact resistance, can be obtained by apolycarbonate resin composition comprising a polycarbonate resin (b) anda polycarbonate resin (a) having a pencil hardness higher than thepolycarbonate resin (b) and having a specific glass transitiontemperature (Tg(a)).

More specifically, it was found that by mixing a resin having Tg in aspecific range, physical properties, particularly the surface hardnessof a polycarbonate resin composition are specifically improved. Further,it was found that a polycarbonate resin composition of the presentinvention having a flame retardant incorporated in the polycarbonateresin has favorable flame retardancy.

That is, the present invention provides the following.

<1> A polycarbonate resin composition comprising at least apolycarbonate resin (a) and a polycarbonate resin (b) having structuralunits different from the polycarbonate resin (a), which satisfies thefollowing requirements:

(i) the pencil hardness of the polycarbonate resin (a) as specified byISO 15184 is higher than the pencil hardness of the polycarbonate resin(b) as specified by ISO 15184;

(ii) the glass transition point Tg(a) of the polycarbonate resin (a) andthe glass transition point Tg(b) of the polycarbonate resin (b) satisfythe relation of the following (Formula 1):

Tg(b)−45° C.<Tg(a)<Tg(b)−10° C.  (Formula 1)

and

(iii) the pencil hardness of the polycarbonate resin composition asspecified by ISO 15184 is higher by at least two ranks than the pencilhardness of the polycarbonate resin (b) as specified by ISO 15184.

<2> A polycarbonate resin composition comprising at least apolycarbonate resin (a) and a polycarbonate resin (b) having structuralunits different from the polycarbonate resin (a), which satisfies thefollowing requirements:

(i) the pencil hardness of the polycarbonate resin (a) as specified byISO 15184 is higher than the pencil hardness of the polycarbonate resin(b) as specified by ISO 15184; and

(ii) the ratio of the intrinsic viscosity [η](a) of the polycarbonateresin (a) to the intrinsic viscosity [η](b) of the polycarbonate resin(b), [η](a)/[η](b), is at least 0.1 and at most 0.65.

<3> The polycarbonate resin composition according to the above <1> or<2>, wherein the ratio of the viscosity average molecular weight Mv(a)of the polycarbonate resin (a) to the viscosity average molecular weightMv(b) of the polycarbonate resin (b), Mv(a)/Mv(b), is at least 0.1 andat most 2.0.<4> The polycarbonate resin composition according to any one of theabove <1> to <3>, wherein the weight ratio of the polycarbonate resin(a) to the polycarbonate resin (b) in the polycarbonate resincomposition is within a range of from 1:99 to 45:55.<5> The polycarbonate resin composition according to any one of theabove <1> to <4>, wherein the pencil hardness of the polycarbonate resin(a) as specified by ISO 15184 is at least F.<6> The polycarbonate resin composition according to any one of theabove <1> to <5>, wherein the pencil hardness of the polycarbonate resincomposition as specified by ISO 15184 is at least HB.<7> The polycarbonate resin composition according to any one of theabove <1> to <6>, wherein the above Tg(a) and Tg(b) satisfy the relationof the following (Formula 2):

Tg(b)−30° C.<Tg(a)<Tg(b)−15° C.  (Formula 2)

<8> The polycarbonate resin composition according to any one of theabove <1> to <7>, wherein the polycarbonate resin (a) is a polycarbonateresin having at least structural units derived from a compoundrepresented by the following formula (1):

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.<9> The polycarbonate resin composition according to any one of theabove <1> to <8>, wherein the polycarbonate resin (a) is a polycarbonateresin having at least structural units derived from at least onecompound selected from the group consisting of the following formulae(1a) to (1c):

<10> The polycarbonate resin composition according to any one of theabove <1> to <9>, wherein the polycarbonate resin (b) is a polycarbonateresin having mainly structural units derived from a compound representedby the following formula (2):

<11> The polycarbonate resin composition according to any one of theabove <1> to <10>, which has a yellowness index (YI) of at most 4.0.<12> The polycarbonate resin composition according to any one of theabove <1> to <11>, which further contains a flame retardant.<13> A method for producing the polycarbonate resin composition asdefined in any one of the above <1> to <12>, which comprisesmelt-kneading the polycarbonate resin (a) and the polycarbonate resin(b).<14> A method for producing the polycarbonate resin composition asdefined in any one of the above <1> to <12>, which comprisesdry-blending the polycarbonate resin (a) and the polycarbonate resin(b).<15> An injection-molded article, which is obtained by injection-moldingthe polycarbonate resin composition as defined in any one of the above<1> to <12>.<16> An extruded article, which is obtained by extruding thepolycarbonate resin composition as defined in any one of the above <1>to <12>.<17> The extruded article according to the above <16>, which is a sheetor a film.<18> A molded article of polycarbonate resin, comprising thepolycarbonate resin composition as defined in any one of the above <8>to <12>, wherein the ratio of the content [S] of the structural units(a) derived from a compound represented by the following formula (1) onthe surface of the molded article of polycarbonate resin to the content[T] in the entire molded article of polycarbonate resin ([S]/[T]) ishigher than 1.00 and at most 2.00:

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.<19> The molded article of polycarbonate resin according to the above<18>, which is an injection-molded article.<20> The molded article of polycarbonate resin according to the above<18> or <19>, wherein the ratio of the content [S] of the structuralunits (a) on the surface of the molded article of polycarbonate resin tothe content [T] in the entire molded article of polycarbonate resin([S]/[T]) is at least 1.01 and at most 1.50.<21> The molded article of polycarbonate resin according to any one ofthe above <18> to <20>, wherein the pencil hardness on the surface ofthe molded article of polycarbonate resin as specified by ISO 15184 isat least HB.<22> The molded article of polycarbonate resin according to any one ofthe above <18> to <21>, wherein the structural units (a) are structuralunits derived from at least one compound selected from the groupconsisting of the following formulae (1a) to (1c):

<23> The molded article of polycarbonate resin according to any one ofthe above <18> to <22>, wherein the polycarbonate resin (b) is apolycarbonate resin having mainly structural units (b) derived from acompound represented by the following formula (2):

<24> The molded article of polycarbonate resin according to any one ofthe above <18> to <23>, which comprises at least a polycarbonate resin(a) having structural units (a) derived from a compound represented bythe formula (1) and a polycarbonate resin (b) having structural units(b) different from the structural units (a) and having a structuredifferent from the polycarbonate resin (a).<25> The molded article of polycarbonate resin according to any one ofthe above <18> to <24>, wherein the pencil hardness of the polycarbonateresin (a) as specified by ISO 15184 is higher than the pencil hardnessof the polycarbonate resin (b) as specified by ISO 15184.<26> The molded article of polycarbonate resin according to any one ofthe above <18> to <25>, wherein the pencil hardness of the polycarbonateresin (a) as specified by ISO 15184 is at least F.<27> The molded article of polycarbonate resin according to any one ofthe above <18> to <26>, wherein the viscosity average molecular weightof the polycarbonate resin (a) is higher than the viscosity averagemolecular weight of the polycarbonate resin (b).<28> A method for producing the molded article of polycarbonate resin asdefined in any one of the above <18> to <27>, comprising at least apolycarbonate resin (a) having structural units (a) derived from acompound represented by the following formula (1) and a polycarbonateresin (b) having structural units (b) different from the structuralunits (a), which comprises melt-kneading or dry-blending thepolycarbonate resin (a) and the polycarbonate resin (b), followed bymolding, wherein the viscosity average molecular weight of thepolycarbonate resin (a) is higher than the viscosity average molecularweight of the polycarbonate resin (b):

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.<29> The method for producing the molded article of polycarbonate resinaccording to the above <28>, wherein the structural units (a) arestructural units derived from at least one compound selected from thegroup consisting of the following formulae (1a) to (1c):

<30> The method for producing the molded article of polycarbonate resinaccording to the above <28> or <29>, wherein the structural units (b)are mainly structural units derived from a compound of the followingformula (2):

<31> The method for producing the molded article of polycarbonate resinaccording to any one of the above <28> to <30>, wherein the molding isinjection-molding.

Advantageous Effects of Invention

According to the present invention, it is possible to obtain apolycarbonate resin composition having a particularly excellent surfacehardness, having favorable flame retardancy, and having excellent heatresistance, moldability (fluidity), color, impact resistance and thelike. That is, by a polycarbonate resin composition comprising apolycarbonate resin (b) and a polycarbonate resin (a) having a specificglass transition point, effects of increasing the surface hardness andthe like can be obtained, without impairing the physical properties ofthe polycarbonate resin (b). For example, in a case where a bisphenol Atype polycarbonate resin is used as the polycarbonate resin (b), thesurface hardness which is a disadvantage of the bisphenol A typepolycarbonate resin can be improved while minimizing a decrease in theimpact resistance, the transparency, the color and the like which arecharacteristics of the bisphenol A type polycarbonate resin.

DESCRIPTION OF EMBODIMENTS

The polycarbonate resin composition of the present invention is apolycarbonate resin composition comprising at least a polycarbonateresin (a) and a polycarbonate resin (b) having structural unitsdifferent from the polycarbonate resin (a), which satisfies theafter-mentioned requirements (i) to (iii).

First, the requirement (i) is that the pencil hardness of thepolycarbonate resin (a) constituting the polycarbonate resin compositionof the present invention as specified by ISO 15184 is higher than thepencil hardness of the polycarbonate resin (b) as specified by ISO15184.

The pencil hardness of the polycarbonate resin or the polycarbonateresin composition specified in the present invention is the pencilhardness measured in the form of an injection-molded article, asdescribed in the evaluation method “(1) pencil hardness of moldedarticle” in Examples in detail. Hereinafter, in this specification, “thepencil hardness” means this pencil hardness of an injection-moldedarticle, unless otherwise specified.

If the pencil hardness of the polycarbonate resin (a) is equal to orlower than the pencil hardness of the polycarbonate resin (b), thepencil hardness of the polycarbonate resin composition may be low, andthe surface of a molded article is likely to be scarred.

A favorable pencil hardness of the polycarbonate resin (a) is at least Fby the pencil hardness as specified by ISO 15184. If the pencil hardnessof the polycarbonate resin (a) is less than F, the pencil hardness ofthe polycarbonate resin composition may not sufficiently be improved insome cases.

As the requirement (ii), it is required that the glass transition pointTg(a) of the polycarbonate resin (a) and the glass transition pointTg(b) of the polycarbonate resin (b) satisfy the relation of thefollowing (Formula 1):

Tg(b)−45° C.<Tg(a)<Tg(b)−10° C.  (Formula 1)

Here, if Tg(a) is equal to or lower than Tg(b)−45° C., the glasstransition temperature of the obtainable polycarbonate resin compositiontends to be too low, thus lowering the heat resistance in some cases. Onthe other hand, if Tg(a) is equal to or higher than Tg(b)−10° C., theeffect of increasing the surface hardness of the obtainablepolycarbonate resin composition tends to be small, and as a result, thesurface may easily be scarred. Further, the melt viscosity of theobtainable polycarbonate resin composition may be high, whereby thefluidity tends to be low, the moldability tend to be poor, and nofavorable molded article may be obtained.

Particularly from the viewpoint of the balance between the heatresistance and the moldability, Tg(a) and Tg(b) preferably satisfy therelation of the following (Formula 2):

Tg(b)−30° C.<Tg(a)<Tg(b)−15° C.  (Formula 2)

As the requirement (iii), it is essential that the pencil hardness ofthe polycarbonate resin composition of the present invention asspecified by ISO 15184 is higher by at least two ranks than the pencilhardness of the polycarbonate resin (b) as specified by ISO 15184, andit is preferably higher by at least three ranks.

The pencil hardness ranks are, from lower ranks, 2B, B, HB, F, H, 2H, 3Hand 4H, and the pencil hardness of the polycarbonate resin compositionas specified by ISO 15184 being higher by at least two ranks than thepencil hardness of the polycarbonate resin (b) as specified by ISO 15184means, for example, a pencil hardness of at least HB when the pencilhardness of the polycarbonate resin (b) as specified by ISO 15184 is 2B,a pencil hardness of at least F when the pencil hardness of thepolycarbonate resin (b) is B, and a pencil hardness of at least H whenthe pencil hardness of the polycarbonate resin (b) as specified by ISO15184 is HB.

If the pencil hardness of the polycarbonate resin composition asspecified by ISO 15184 is not higher by at least two ranks than thepencil hardness of the polycarbonate resin (b) as specified by ISO15184, the pencil hardness of the polycarbonate resin composition asspecified by ISO 15184 may be low, and the surface of the molded articleis likely to be scarred in some cases.

Further, the polycarbonate resin composition of the present invention isa polycarbonate resin composition comprising at least a polycarbonateresin (a) and a polycarbonate resin (b) having structural unitsdifferent from the above polycarbonate resin, which satisfies theafter-mentioned requirements (1) and (2).

First, the requirement (1) is that the pencil hardness of thepolycarbonate resin (a) constituting the polycarbonate resin compositionof the present invention as specified by ISO 15184 is higher than thepencil hardness of the polycarbonate resin (b) as specified by ISO15184.

If the pencil hardness of the polycarbonate resin (a) is equal to orlower than the pencil hardness of the polycarbonate resin (b), thepencil hardness of the polycarbonate resin composition may be low, andthe surface of a molded article is likely to be scarred.

A favorable pencil hardness of the polycarbonate resin (a) is at least Fby the pencil hardness as specified by ISO 15184. If the pencil hardnessof the polycarbonate resin (a) is less than F, the pencil hardness ofthe polycarbonate resin composition may not sufficiently be improved insome cases.

As the requirement (2), the ratio of the intrinsic viscosity [η](a) ofthe polycarbonate resin (a) to the intrinsic viscosity [η](b) of thepolycarbonate resin (b), [η](a)/[η](b), is required to be within a rangeof at least 0.1 and at most 0.65, preferably within a range of at least0.15 and at most 0.6.

If [η](a)/[η](b) is too low, the surface hardness of the polycarbonateresin composition may not sufficiently be improved, and if [η](a)/[η](b)is too high, the melt viscosity of the polycarbonate resin compositionmay be too high, whereby the fluidity may be decreased, and themoldability may be low.

In the present invention, “having different structural units” means [I]“having different types of structural units” in a case where each of thepolycarbonate resin (a) and the polycarbonate resin (b) is ahomopolymer, and means [II] (A) having different types of structuralunits or (B) having the same type of structural units and having adifferent compositional ratio of the structural units in a case where atleast one of the polycarbonate resin (a) and the polycarbonate resin (b)is a copolymer.

That is, a specific example of the above [I] is a case where thepolycarbonate resin (a) is a homopolymer comprising structural units (a)and the polycarbonate resin (b) is a homopolymer comprising structuralunits (b).

A specific example of [II] (A) is a case where the polycarbonate resin(a) is a copolymer comprising structural units (a) and structural units(c), and the polycarbonate resin (b) is a copolymer comprisingstructural units (b) and structural units (c).

A specific example of the above [II] (B) is a case where each of thepolycarbonate resin (a) and the polycarbonate resin (b) comprisesstructural units (a) and structural units (b), however, thepolycarbonate resin (a) and the polycarbonate resin (b) are different inthe ratio of the structural units (a) to the structural units (b).

Further, the structural units (c) are structural units different fromboth the structural units (a) and the structural units (b).

The present invention relates to a molded article of polycarbonate resinhaving structural units (a) derived from a compound represented by thefollowing formula (1) and structural units (b) different from thestructural units (a), wherein the ratio of the content [S] of thestructural units (a) on the surface of the molded article ofpolycarbonate resin to the content [T] in the entire molded article ofpolycarbonate resin ([S]/[T]) is higher than 1.00 and at most 2.00:

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.

The present invention is characterized in that in the molded article ofpolycarbonate resin having the above two types of structural units, theratio of the content [S] of the structural units (a) on the surface ofthe molded article of polycarbonate resin to the content [T] in theentire molded article of polycarbonate resin ([S]/[T]) is higher than1.00 and at most 2.00, preferably at least 1.01 and at most 1.50,further preferably at least 1.10 and at most 1.20.

That is, in the molded article of polycarbonate resin of the presentinvention, the content of the structural units (a) on the surface of themolded article of polycarbonate resin is higher than the content of thestructural units (a) in the entire molded article of polycarbonateresin.

As mentioned above, a molded article of polycarbonate resin containing alarger amount of the structural units (a) on the surface of the moldedarticle of polycarbonate resin, has a remarkably improved surfacehardness, has a favorable color, and has improved impact resistance.

Particularly when the above [S]/[T] is at least 1.01 and at most 1.50, amolded article of polycarbonate resin which is more excellent in thesurface hardness and the impact resistance will be obtained.

The content [S] of the structural units (a) on the surface of the moldedarticle of polycarbonate resin and the content [T] of the structuralunits (a) in the entire molded article of polycarbonate resin can beobtained by an NMR method. More specifically, the molar composition ofeach structural units can be obtained by the integrated intensity ratioof signals characteristics of a dihydroxy compound observed by ¹H-NMRmeasurement of a deuterochloroform solution of the molded article ofpolycarbonate resin using a nuclear magnetic resonance apparatus (NMRapparatus). The weight ratio of each structural units is determined fromthe obtained molar composition and the formula weight of each structuralunits.

Specific methods of obtaining the content [S] of the structural units(a) on the surface of the molded article of polycarbonate resin and thecontent [T] of the structural units (a) in the entire molded article ofpolycarbonate resin are as follows.

(I) Content [S] of Structural Units (a) on the Surface of Molded Articleof Polycarbonate Resin

The entire molded article of polycarbonate resin is immersed inmethylene chloride at room temperature (25° C.). 5 Seconds afterinitiation of immersion, the molded article of polycarbonate resin istaken out from methylene chloride to obtain a methylene chloridesolution. Methylene chloride is removed from the methylene chloridesolution to obtain a residue. The residue is dissolved indeuterochloroform, and the obtained solution is subjected to measurementby ¹H-NMR method.

From the signal intensity of the structural units (a) and the signalintensities of other structural units in the obtained ¹H-NMR spectrum,the proportion of the structural units (a) to all the structural unitsobtained in total is calculated and regarded as the content [S] (wt %)of the structural units (a) on the surface of the molded article ofpolycarbonate resin.

(II) Content [T] of Structural Units (a) in the Entire Molded Article ofPolycarbonate Resin

The entire molded article of polycarbonate resin is immersed inmethylene chloride at room temperature (25° C.) and completely dissolvedto obtain a methylene chloride solution. About 50 g of the methylenechloride solution is taken, and methylene chloride is removed from themethylene chloride solution to obtain a residue. The residue isdissolved in deuterochloroform, and the obtained solution is subjectedto measurement by ¹H-NMR method.

From the signal intensity of the structural units (a) and the signalintensities of other structural units in the obtained ¹H-NMR spectrum,the proportion of the structural units (a) to all the structural unitsobtained in total is calculated and regarded as the content [T] (wt %)of the structural units (a) in the entire molded article.

The molded article of polycarbonate resin of the present invention ispreferably an injection-molded article.

An injection-molded article has advantages in that molded articleshaving a complicated shape can be molded in a high cycle rate.

The Charpy impact strength of the molded article of polycarbonate resinof the present invention is properly determined depending upon theshape, the purpose of use and the like of a final article, and isusually at least 8 kJ/m², preferably at least 10 kJ/m². If the Charpyimpact strength is less than 8 kJ/m², the molded article ofpolycarbonate resin tends to be easily broken. The Charpy impactstrength of the molded article of polycarbonate resin can be determinedby a measurement method based on JIS K7111. The specific measurementmethod will be described in detail in Examples.

(Content of Structural Units in Molded Article of Polycarbonate Resin)

The content (average content) of the structural units (a) in the moldedarticle of polycarbonate resin of the present invention is notparticularly limited, and is usually less than 50 wt %, preferably atmost 20 wt %, based on 100 wt % of all the structural units (the totalof the structural units (a), the structural units (b) and otherstructural units) constituting the polycarbonate resin. Further, thelower limit of the content of the structural units (a) is 1 wt %.

The content of the structural units in the molded article ofpolycarbonate resin can be obtained by the NMR method, as describedabove.

The molded article of polycarbonate resin of the present invention ispreferably a molded article of polycarbonate resin comprising at least apolycarbonate resin (a) having structural units (a) derived from acompound represented by the above formula (1) and a polycarbonate resin(b) having structural units (b) different from the structural units (a)and having a structure different from the polycarbonate resin (a), inview of easy production.

The polycarbonate resin (b) is a polycarbonate resin having structuralunits (b) different from the structural units (a) and having a structuredifferent from the polycarbonate resin (a). That is, the polycarbonateresin (b) has “a structure different” from the polycarbonate resin (a)not only when the polycarbonate resin (a) is a homopolymer comprisingstructural units (a) and the polycarbonate resin (b) is a homopolymercomprising structural units (b), but also when the polycarbonate resin(b) is a copolymer having structural units (a) as structural units otherthan the structural units (b).

Further, in a case where the molded article of polycarbonate resin ofthe present invention comprises the above polycarbonate resin (a) andpolycarbonate resin (b), the viscosity average molecular weight of thepolycarbonate resin (a) is preferably higher than the viscosity averagemolecular weight of the polycarbonate resin (b). It is estimated that amolded article of polycarbonate resin having a different content of thestructural units between on the surface of the molded article ofpolycarbonate resin and in the interior of the molded article ofpolycarbonate resin can be obtained by such a difference in theviscosity average molecular weight.

Further, in the polycarbonate resin composition of the presentinvention, the ratio of the viscosity average molecular weight Mv(a) ofthe polycarbonate resin (a) to the viscosity average molecular weightMv(b) of the polycarbonate resin (b), Mv(a)/Mv(b), is preferably atleast 0.1 and at most 2.0, more preferably at least 0.4 and at most 1.8.If Mv(a)/Mv(b) is low, the impact resistance may be decreased. Further,if Mv(a)/Mv(b) is high, the effect of improving the surface hardnesstends to be small, and the surface hardness of the polycarbonate resincomposition may be low. Further, the melt viscosity tends to be veryhigh, whereby the fluidity will be deteriorated and the moldability ispoor in some cases.

The viscosity average molecular weight Mv(a) of the polycarbonate resin(a) is usually within a range of from 1,000 to 100,000, preferably from3,000 to 50,000, more preferably from 5,000 to 30,000, furtherpreferably from 5,000 to 20,000, most preferably from 6,000 to 15,000.If Mv(a) is too high, the melt viscosity of the polycarbonate resincomposition tends to be high, and the effect of improving the surfacehardness may be small, such being unfavorable. Further, if Mv(a) is toolow, the effect of improving the surface hardness of the polycarbonateresin composition tends to be small, and the impact resistance, thestrength and the like may be low in some cases, such being unfavorable.

The viscosity average molecular weight Mv(b) of the polycarbonate resin(b) is usually within a range of from 1,000 to 100,000, preferably from5,000 to 50,000, more preferably from 10,000 to 40,000, furtherpreferably from 15,000 to 30,000. If Mv(b) is too high, the meltviscosity of the polycarbonate resin composition tends to be high, andthe fluidity may be decreased, such being unfavorable. Further, if Mv(b)is too low, the effect of improving the surface hardness of the resincomposition tends to be small, and the impact resistance, the strengthand the like may be low in some cases, such being unfavorable.

The weight ratio of the polycarbonate resin (a) to the polycarbonateresin (b) in the polycarbonate resin composition is preferably from 1:99to 99:1, more preferably from 1:99 to 45:55, further preferably from5:95 to 40:60, particularly preferably from 10:90 to 30:70. If theproportion of the polycarbonate resin (a) is high, a decrease in theimpact resistance, a decrease in the heat resistance and deteriorationof the color may occur, and if the proportion of the polycarbonate resin(a) is low, the pencil hardness may be decreased.

The yellowness index (YI) of the polycarbonate resin composition of thepresent invention is usually at most 4.0, preferably at most 3.5,further preferably at most 3.0, particularly preferably at most 2.5. IfYI is too high, the color tends to be deteriorated, the design as amolded article tends to be poor, and particularly in a molded articlewhich is required to be colored, the brightness may be insufficient, andthe color may be smoky.

The melt viscosity of the polycarbonate resin composition of the presentinvention is preferably at most 15,000 Poise, more preferably at most11,000 Poise, further preferably at most 8,000 Poise, particularlypreferably at most 5,000 Poise, at a temperature of 280° C. at a shearrate of 122 sec⁻¹. If the melt viscosity is at least 15,000 poise, thefluidity may remarkably be decreased, and the moldability may beimpaired. The melt viscosity is a value measured by a capillaryrheometer “Capirograph 1C” (manufactured by Toyo Seiki Seisaku-sho,Ltd.).

The pencil hardness of the polycarbonate resin composition of thepresent invention as specified by ISO 15184 is usually at least HB,preferably at least F, more preferably at least H. If the pencilhardness is low, the surface hardness tends to be low, and when thepolycarbonate resin composition is molded into a molded article, it iseasily scarred in some cases.

The Charpy impact strength of the polycarbonate resin composition isproperly determined by e.g. the shape and the application of a finalarticle, and is usually at least 8. If it is less than 8, the finalarticle may easily be broken.

The polycarbonate resin (a) and the polycarbonate resin (b) havingstructural units different from the polycarbonate resin (a) are notparticularly limited so long as the above requirements are satisfied. Asdescribed above, the polycarbonate resin (a) is a resin having arelatively high pencil hardness, and the polycarbonate resin (b) is aresin having a relatively low pencil hardness.

Now, polycarbonate resins suitable as the polycarbonate resin (a) andthe polycarbonate resin (b) having structural units different from thepolycarbonate resin (a), constituting the polycarbonate resincomposition of the present invention, will be described.

<Polycarbonate Resin (a)>

As the polycarbonate resin (a), first, a polycarbonate resin having atleast structural units derived from a compound represented by thefollowing formula (1) may be mentioned as a suitable example:

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.

In the above formula (1), as each of R¹ and R², the substituted ornon-substituted C₁₋₂₀ alkyl group may, for example, be a methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl,sec-pentyl, n-hexyl, n-heptyl or n-octyl group, and the substituted ornon-substituted aryl group may, for example, be a phenyl, benzyl, tolyl,4-methylphenyl or naphthyl group.

As each of R³ and R⁴, the substituted or non-substituted C₁₋₂₀ alkylgroup may, for example, be a methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, n-hexyl,n-heptyl or n-octyl group, and the substituted or non-substituted arylgroup may, for example, be a phenyl, benzyl, tolyl, 4-methylphenyl ornaphthyl group.

Among them, each of R¹ and R² is preferably a methyl, ethyl, n-propyl or4-methylphenyl group, particularly preferably a methyl group. Each of R³and R⁴ is preferably a hydrogen atom, a methyl, ethyl, n-propyl or4-methylphenyl group, particularly preferably a hydrogen atom. Here, thebonding positions of R¹, R², R³ and R⁴ in the formula (1) are optionalpositions selected from 2-, 3-, 5- and 6-positions relative to X on thephenyl rings, and are preferably 3-position or 5-position.

Further, in the formula (1), in a case where X is a substituted ornon-substituted alkylidene group or a carbonyl group, it is representedby the following structural formulae. As X, the oxidized or not-oxidizedsulfur atom may, for example, be —S— or —SO₂—.

wherein each of R⁵ and R⁶ which are independent of each other, is ahydrogen atom, a substituted or non-substituted C₁₋₂₀ alkyl group or asubstituted or non-substituted aryl group, Z is a substituted ornon-substituted C₄₋₂₀ alkylene group or a polymethylene group, and n isan integer of from 1 to 10.

As each of R⁵ and R⁶, the substituted or non-substituted C₁₋₂₀ alkylgroup may, for example, be a methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, n-hexyl,n-heptyl or n-octyl group, and the substituted or non-substituted arylgroup may, for example, be a phenyl, benzyl, tolyl, 4-methylphenyl ornaphthyl group.

Among them, each of R⁵ and R⁶ is preferably a methyl, ethyl, n-propyl or4-methylphenyl group, particularly preferably a methyl group. It isparticularly preferred that both of R⁵ and R⁶ are methyl groups and n is1, that is, X in the formula (1) is an isopropylidene group.

Z in the formula (1) is bonded to the carbon atom bonded to the twophenyl groups, and forms a substituted or non-substituted bivalentcarbon ring. The bivalent carbon ring may, for example, be a (preferablyC₄₋₁₂) cycloalkylidene group such as a cyclopentylidene,cyclohexylidene, cycloheptylidene, cyclododecylidene or adamantylidenegroup, and the substituted carbon ring may, for example, be such a grouphaving a methyl substituent or an ethyl substituent. Among them,preferred is a cyclohexylidene group, a methyl-substitutedcyclohexylidene group or a cyclododecylidene group.

Among polycarbonate resins (a) having at least structural units derivedfrom a compound represented by the above formula (1), a polycarbonateresin having structural units derived from at least one compoundselected from the group consisting of the following formulae (1a) to(1i) is suitably used.

Among the above compounds, a polycarbonate resin having structural unitsderived from at least one compound selected from the group consisting ofthe above formulae (1a) to (1c) is more suitably used.

The polycarbonate resin (a) may contain structural units other than thestructural units derived from the compound represented by the aboveformula (1), within a range not to impair the performance.

Such structural units are not particularly limited and may, for example,be specifically structural units derived from an alicyclic dihydroxycompound such as 2,2-bis(4-hydroxyphenyl)propane (hereinafter sometimesreferred to as “bisphenol A”) or absolute sugar alcohol, or a cyclicether compound such as spiroglycol.

From the viewpoint of easiness of production of the molded article ofpolycarbonate resin of the present invention, the content of thestructural units (a) in the polycarbonate resin (a) is preferably atleast 50 wt %, more preferably at least 75 wt %, particularly preferablyat least 95 wt % (including 100 wt %) based on 100 wt % of all thestructural units in the polycarbonate resin (a).

The content of the structural units in the polycarbonate resin (a) canbe obtained by the NMR method described in the above molded article ofpolycarbonate resin.

<Polycarbonate Resin (b)>

Then, as the polycarbonate resin (b), a polycarbonate resin havingstructural units derived from at least one compound selected from thegroup consisting of the following formulae (2) to (13) is suitably used,and a bisphenol A type polycarbonate resin having mainly structuralunits derived from bisphenol A represented by the following formula (2)is more suitably used.

Here, “having mainly structural units derived from bisphenol A” meansthat among the structural units constituting the polycarbonate resin(b), at least 50 wt %, preferably at least 80 wt %, more preferably atleast 90 wt % are structural units derived from bisphenol A.

Here, the polycarbonate resin (b) contains the structural units (b)which are structural units other than the structural units (a) and mayhave structural units other than the structural units (b). Accordingly,the polycarbonate resin (b) may have structural units (a) (that is, thepolycarbonate resin (b) is a copolymer having the structural units (a)and the structural units (b)).

On the other hand, if the polycarbonate resin (b) contains a largeamount of the structural units (a), the color may be deteriorated, orthe impact strength may be decreased, and accordingly, the proportion ofthe structural units (a) contained in the polycarbonate resin (b) ispreferably less than 50 wt %, more preferably less than 25 wt %, andpreferably less than 5 wt % (including 0 wt %), based on 100 wt % of allthe structural units constituting the polycarbonate resin (b).

The content of the structural units in the polycarbonate resin (b) canbe obtained by the NMR method. Specifically, the molar composition ofeach structural units can be obtained from the integrated intensityratio of signals characteristics of a dihydroxy compound used when thepolycarbonate resin (b) is prepared, observed by ¹H-NMR measurement of adeuterochloroform solution of the polycarbonate resin (b) using anuclear magnetic resonance apparatus (NMR apparatus). The weight ratioof each structural units is determined from the obtained molarcomposition and the formula weight of each structural units.

<Method for Producing Polycarbonate Resin>

Now, the method for producing the polycarbonate resin (a) and thepolycarbonate resin (b) of the present invention will be described below(hereinafter “the polycarbonate resin (a) and the polycarbonate resin(b)” will generally be referred to as “polycarbonate resin” in somecases.)

The polycarbonate resin of the present invention is obtainable bypolymerization by using a dihydroxy compound and a carbonyl compound.Specifically, there are an interfacial polycondensation method(hereinafter sometimes referred to as “interfacial method”) forproducing a polycarbonate resin by reacting a dihydroxy compound andcarbonyl chloride (hereinafter sometimes referred to as “CDC” or“phosgene” at an interface between an organic phase and an aqueous phasewhich are not miscible optionally, and a melt polycondensation method(hereinafter sometimes referred to as “melt method”) for producing apolycarbonate resin by subjecting a dihydroxy compound and a carbonylcompound to an ester exchange reaction in a molten state in the presenceof an ester exchange reaction catalyst.

Now, each of the interfacial method and the melt method may specificallybe described.

<Interfacial Method>

The polycarbonate resin of the present invention by the interfacialmethod is usually obtained in such a manner that an alkaline aqueoussolution of a dihydroxy compound is prepared (raw material preparationstep), the interfacial polycondensation reaction of the dihydroxycompound and phosgene (COCl₂) is carried out in an organic solvent inthe presence of, for example, an amine compound, as a condensationcatalyst, followed by steps of neutralization, washing with water anddrying to obtain the polycarbonate resin. Specifically, thepolycarbonate resin production process by the interfacial methodcomprises at least a raw material preparation step of preparing rawmaterials such as a monomer component, an oligomerization step to carryout an oligomerization reaction, a polycondensation step of carrying outa polycondensation reaction using the oligomer, a washing step ofwashing the reaction liquid after the polycondensation reaction byalkali washing, acid washing and water washing, a polycarbonate resinisolation step of pre-concentrating the washed reaction liquid andisolating the polycarbonate resin after granulation, and a drying stepof drying isolated polycarbonate resin particles.

In the interfacial method, usually an organic solvent is used.

Now, the respective steps will be described.

(Raw Material Preparation Step)

In the raw material preparation step, in a raw material preparationtank, a raw material of e.g. an alkaline aqueous solution of a dihydroxycompound containing a dihydroxy compound, an aqueous solution of a metalcompound such as sodium hydroxide (NaOH) or magnesium hydroxide(Mg(OH)₂), demineralized water (DMW) and further as the case requires, areducing agent such as hydrosulfite (HS) is prepared.

(Dihydroxy Compound)

As the dihydroxy compound which is a raw material of the polycarbonateresin of the present invention, specifically, dihydroxy compoundsrepresented by the formulae (1a) to (1i) represented by the aboveformula (1) and the formulae (2) to (13) may, for example, be mentioned.

(Metal Compound)

The metal compound is usually preferably a hydroxide, such as sodiumhydroxide, lithium hydroxide, potassium hydroxide, magnesium hydroxideor calcium hydroxide. Among them, sodium hydroxide is particularlypreferred.

The proportion of the metal compound to the dihydroxy compound isusually from 1.0 to 1.5 (equivalent ratio), preferably from 1.02 to 1.04(equivalent ratio). If the proportion of the metal compound isexcessively high or excessively low, such may influence the terminalgroups of the carbonate oligomer obtainable in the after-mentionedoligomerization step, and as a result, the polycondensation reactiontends to be abnormal.

(Oligomerization Step)

Then, in the oligomerization step, in a predetermined reactor, thealkaline aqueous solution of the dihydroxy compound prepared in the rawmaterial preparation step and phosgene (CDC) are subjected to a phosgenereaction of the dihydroxy compound in the presence of an organic solventsuch as methylene chloride (CH₂Cl₂).

Then, to the mixed liquid after the phosgene reaction of the dihydroxycompound, a condensation catalyst such as triethylamine (TEA) and achain stopper such as p-t-butylphenol (pTBP) are added, to carry out anoligomerization reaction of the dihydroxy compound.

Then, after further oligomerization reaction is allowed to proceed, theoligomerization reaction liquid of the dihydroxy compound is introducedinto a predetermined static separation tank, an organic phase containingthe carbonate oligomer and an aqueous phase are separated, and theseparated organic phase is supplied to a polycondensation step.

Here, the retention time in the oligomerization step after the alkalineaqueous solution of the dihydroxy compound is supplied to the reactor inwhich the phosgene reaction of the dihydroxy compound is carried outuntil the oligomerization reaction liquid enters the static separationtank, is usually at most 120 minutes, preferably from 30 to 60 minutes.

(Phosgene)

Phosgene used in the oligomerization step is usually used in the form ofliquid or gas. The preferred amount of use of CDC in the oligomerizationstep is properly selected depending upon the reaction conditions,particularly the reaction temperature and the concentration of thedihydroxy compound in the aqueous phase and is not particularly limited.Usually, the amount of CDC is from 1 to 2 mol, preferably from 1.05 to1.5 mol, per 1 mol of the dihydroxy compound. If the amount of use ofCDC is excessively large, unreacted CDC tends to increase, and the unitsmay remarkably be deteriorated. Further, if the amount of use of CDC isexcessively small, the chloroformate group amount tends to beinsufficient, and no appropriate molecular weight elongation tends to beconducted.

(Organic Solvent)

In the oligomerization step, usually an organic solvent is used. Theorganic solvent may be any optional inert organic solvent in whichphosgene and reaction products such as the carbonate oligomer and thepolycarbonate resin are dissolved under the reaction temperature and thereaction pressure in the oligomerization step, and which is not misciblewith water (or which does not form a solution with water).

Such an inert organic solvent may, for example, be an aliphatichydrocarbon such as hexane or n-heptane; a chlorinated aliphatichydrocarbon such as dichloromethane, chloroform, carbon tetrachloride,dichloroethane, trichloroethane, tetrachloroethane, dichloropropane or1,2-dichloroethylene; an aromatic hydrocarbon such as benzene, tolueneor xylene, a chlorinated aromatic hydrocarbon such as chlorobenzene,o-dichlorobenzene or chlorotoluene; or a substituted aromatichydrocarbon such as nitrobenzene or acetophenone.

Among them, a chlorinated hydrocarbon such dichloromethane orchlorobenzene is suitably used. Such an inert organic solvent may beused alone or as a mixture with another solvent.

(Condensation Catalyst)

The oligomerization reaction may be carried out in the presence of acondensation catalyst. The timing of addition of the condensationcatalyst is preferably after CDC is consumed. The condensation catalystmay optionally be selected among many condensation catalysts which havebeen used for a two-phase interfacial condensation method. It may, forexample, be trialkylamine, M-ethylpyrrolidone, N-ethylpiperidine,N-ethylmorpholine, N-isopropylpiperidine or N-isopropylmorpholine. Amongthem, triethylamine or N-ethylpiperidine is preferred.

(Chain Stopper)

In this embodiment, in the oligomerization step, usually a monophenol isused as the chain stopper. The monophenol may, for example, be phenol; aC₁₋₂₀ alkylphenol such as p-t-butylphenol or p-cresol; or a halogenatedphenol such as p-chlorophenol or 2,4,6-tribromophenol. The amount of useof the monophenol is properly selected depending upon the molecularweight of the obtainable carbonate oligomer, and is usually from 0.5 to10 mol % based on the dihydroxy compound.

In the interfacial method, the molecular weight of the polycarbonateresin is determined by the amount of addition of the chain stopper suchas the monophenol. Accordingly, the timing of addition of the chainstopper is preferably between immediately after completion ofconsumption of the carbonate-forming compound and before the molecularweight elongation starts, with a view to controlling the molecularweight of the polycarbonate resin.

If the monophenol is added when the carbonate-forming compound coexists,a condensate of the monophenol (a diphenyl carbonate) forms in a largeamount, and no polycarbonate resin having a desired molecular weighttends to be obtained. If the timing of addition of the monophenol is toolate, there may be such drawbacks that the molecular weight controltends to be difficult, the obtainable resin may have a specific shoulderon the low molecular side in the molecular weight distribution, andsagging may occur at the time of molding.

(Branching Agent)

Further, in the oligomerization step, an optional branching agent may beused. Such a branching agent may, for example, be2,4-bis(4-hydroxyphenylisopropyl)phenol,2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylphenol,2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane or1,4-bis(4,4′-dihydroxytriphenylmethyl)benzene. Further,2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride or the likemay also be used. Among them, a branching agent having at least threephenolic hydroxy groups is suitable. The amount of use of the branchingagent is properly selected depending upon the degree of branching of theobtainable carbonate oligomer, and is usually from 0.05 to 2 mol % basedon the dihydroxy compound.

In the oligomerization step, in a case where the two-phase interfacialcondensation method is employed, it is preferred that prior to contactof the alkali metal compound aqueous solution or the alkaline earthmetal compound aqueous solution of the dihydroxy compound with phosgene,the organic phase containing the dihydroxy compound and the aqueousphase containing the metal compound are brought into contact with anorganic phase not optionally mixed with water, to form an emulsion.

As a means of forming such an emulsion, it is preferred to use, forexample, a mixing machine such as a stirring machine having apredetermined stirring blade, a dynamic mixer such as a homogenizer, ahomomixer, a colloid mill, a flow jet mixer or an ultrasonic emulsifier,or a static mixer. The emulsion usually has a droplet size of from 0.01to 10 μm, and has emulsion stability.

The emulsified state of the emulsion is usually represented by the Webernumber or P/q (driver power per unit volume). The Weber number ispreferably at least 10,000, more preferably at least 20,000, mostpreferably at least 35,000. Further, as the upper limit, at a level ofat most 1,000,000 is enough. Further, P/q is preferably at least 200kg·m/L, more preferably at least 500 kg·m/L, most preferably at least1,000 kg-m/L.

Contact of the emulsion with CDC is preferably carried out under mixingconditions weaker than the above-described emulsifying conditions, witha view to suppressing dissolution of CDC in the organic phase. The Webernumber is less than 10,000, preferably less than 5,000, more preferablyless than 2,000. Further, P/q is less than 200 kg·m/L, preferably lessthan 100 kg·m/L, more preferably less than 50 kg·m/L. Contact with CDCcan be achieved by introducing CDC into a tubular reactor or a tank-formreactor.

The reaction temperature in the oligomerization step is usually at most80° C., preferably at most 60° C., further preferably within a range offrom 10 to 50° C. The reaction time is properly selected depending uponthe reaction temperature, and is usually from 0.5 minute to 10 hours,preferably from 1 minute to 2 hours. If the reaction temperature isexcessively high, the side reaction cannot be controlled, and the CDCunits tend to be deteriorated. If the reaction temperature isexcessively low, although such is preferred with a view to controllingthe reaction, the refrigeration load tends to increase, thus leading tothe cost increases.

The carbonate oligomer concentration in the organic phase may be such arange that the obtainable carbonate oligomer is soluble, andspecifically, it is at a level of from 10 to 40 wt %. The proportion ofthe organic phase is preferably from 0.2 to 1.0 by the volume ratiobased on the aqueous phase containing the aqueous solution of the metalcompound salt of the dihydroxy compound.

(Polycondensation Step)

Then, in the polycondensation step, the organic phase containing thecarbonate oligomer separated from the aqueous phase in the staticseparation tank is transferred to an oligomer tank having a stirringmachine. In the oligomer tank, a condensation catalyst such astriethylamine (TEA) is further added.

Then, the organic phase stirred in the oligomer tank is introduced intoa predetermined polycondensation reaction tank, and then to thepolycondensation reaction tank, demineralized water (DMW), an organicsolvent such as methylene chloride (CH₂Cl₂) and a sodium hydroxideaqueous solution are supplied, stirred and mixed to carry out apolycondensation reaction of the carbonate oligomer.

The polycondensation reaction liquid in the polycondensation reactiontank is then continuously introduced successively to a plurality ofpolycondensation reaction tanks, whereby the polycondensation reactionof the carbonate oligomer is completed.

Here, in the polycondensation step, the retention time in thepolycondensation reaction tanks in which the polycondensation reactionof the carbonate oligomer is continuously carried out is usually at most12 hours, preferably from 0.5 to 5 hours.

As a preferred embodiment of the polycondensation step, first, theorganic phase containing the carbonate oligomer and the aqueous phaseare separated, and as the case requires, an inert organic solvent isadded to the separated organic phase to adjust the concentration of thecarbonate oligomer. In such a case, the amount of the inert organicsolvent is adjusted so that the concentration of the polycarbonate resinin the organic phase obtainable by the polycondensation reaction is from5 to 30 wt %. Then, water and an aqueous solution containing a metalcompound are newly added, and further, to adjust the polycondensationconditions, preferably a condensation catalyst is added, and thepolycondensation reaction is carried out in accordance with theinterfacial polycondensation method. The ratio of the organic phase tothe aqueous phase in the polycondensation reaction is preferably suchthat the organic phase:the aqueous phase=1:0.2 to 1:1 by the volumeratio.

As the metal compound, the same compound as one used in theabove-described oligomerization step may be mentioned. Particularly,sodium hydroxide is industrially preferred. The amount of use of themetal compound may be at least an amount with which the reaction systemis always alkaline during the polycondensation reaction, and the entireamount may be added all at once at the start of the polycondensationreaction, or the metal compound may be added as properly divided duringthe polycondensation reaction.

If the amount of use of the metal compound is excessively large, ahydrolysis reaction as a side reaction tends to proceed. Accordingly,the concentration of the metal compound contained in the aqueous phaseafter completion of the polycondensation reaction is preferably adjustedto be at least 0.05 N, preferably from 0.05 to 0.3 N.

The temperature of the polycondensation reaction in the polycondensationstep is usually in the vicinity of room temperature. The reaction timeis from 0.5 to 5 hours, preferably at a level of from 1 to 3 hours.

(Washing Step)

Then, after completion of the polycondensation reaction in thepolycondensation reaction tanks, the polycondensation reaction liquid issubjected to alkali washing with an alkaline washing liquid, acidwashing with an acid washing liquid and water washing with washing waterby a known method. The entire retention time in the washing step isusually at most 12 hours, preferably from 0.5 to 6 hours.

(Polycarbonate Resin Isolation Step)

In the polycarbonate resin isolation step, first, the polycondensationreaction liquid containing the polycarbonate resin washed in the washingstep is concentrated to a predetermined solid content concentration toprepare a concentrated liquid. The solid content concentration of thepolycarbonate resin in the concentrated liquid is usually from 5 to 35wt %, preferably from 10 to 30 wt %.

Then, the concentrated liquid is continuously supplied to apredetermined granulation tank, and stirred and mixed with demineralizedwater (DMW) of a predetermined temperature. Further, a granulationtreatment of evaporating the organic solvent while maintaining thesuspended state in water is carried out to form a water slurrycontaining polycarbonate resin granules.

Here, the temperature of demineralized water (DMW) is usually from 37 to67° C., preferably from 40 to 50° C. Further, the solidificationtemperature of the polycarbonate resin by the granulation treatmentcarried out in the granulation tank is usually from 37 to 67° C.,preferably from 40 to 50° C.

The water slurry containing a polycarbonate resin powder continuouslydischarged from the granulation tank is then continuously introducedinto a predetermined separator, and water is separated from the waterslurry.

(Drying Step)

In the drying step, the polycarbonate resin powder after water isseparated from the water slurry in the separator, is continuouslysupplied to a predetermined drying machine, made to stay in apredetermined retention time and then continuously withdrawn. The dryingmachine may, for example, be a fluidized bed drying machine. Further, aplurality of fluidized bed drying machines may be connected in series tocarry out the drying treatment continuously.

Here, the drying machine usually has a heating means such as a heatmedium jacket, and is maintained usually at from 0.1 to 1.0 MPa-G,preferably from 0.2 to 0.6 MPa-G, for example, by water vapor, wherebythe temperature of nitrogen (N₂) which flows in the drying machine ismaintained usually at from 100 to 200° C., preferably from 120 to 180°C.

<Melt Method>

Now, the melt method will be described.

(Dihydroxy Compound)

The dihydroxy compound as a raw material of the polycarbonate resin ofthe present invention may be specifically the same dihydroxy compound asdescribed in the interfacial method.

(Carbonic Diester)

The carbonic diester as the material of the polycarbonate resin of thepresent invention may be a compound represented by the following formula(14).

In the formula (14), A′ is a C₁₋₁₀ linear, branched or cyclic monovalenthydrocarbon group which may be substituted. Two A's may be the same ordifferent.

Furthermore, examples of a substituent in the A′ include a halogen atom,a C₁₋₁₀ alkyl group, a C₁₋₁₀ alkoxy group, a phenyl group, a phenoxygroup, a vinyl group, a cyano group, an ester group, an amide group anda nitro group.

Specific examples of the carbonic diester compound include diphenylcarbonate, a substituted diphenyl carbonate such as ditolyl carbonate, adialkyl carbonate such as dimethyl carbonate, diethyl carbonate anddi-t-butyl carbonate.

Among them, diphenyl carbonate (hereinafter sometimes referred to as“DPC”) and a substituted diphenyl carbonate are preferred. Thosecarbonic diesters may be used alone or as a mixture of two or more ofthem.

Furthermore, the carbonic diester compound may be replaced by adicarboxylic acid or a dicarboxylic ester in an amount of preferably atmost 50 mol %, more preferably at most 30 mol %. The representativeexamples of the dicarboxylic acid or dicarboxylic ester includeterephthalic acid, isophthalic acid, diphenyl terephthalate and diphenylisophthalate. When the carbonic diester is replaced by such adicarboxylic acid or a dicarboxylic ester, a polyester carbonate isobtained.

In the process for producing the polycarbonate resin of the presentinvention by the melt method, as the amount of use of those carbonicdiesters (including the above substitutional dicarboxylic acid ordicarboxylic ester; the same applies hereinafter), the carbonic diestercompound is used in a molar ratio of usually from 1.01 to 1.30 mol,preferably from 1.02 to 1.20 mol per 1 mol of the dihydroxy compound. Ifthe molar ratio of the carbonic diester is excessively low, the esterexchange reaction rate tends to be lowered, whereby production of apolycarbonate resin having a desired molecular weight is difficult, orthe terminal hydroxy group concentration of the obtainable polycarbonateresin tends to be high, thus deteriorating the thermal stability.Further, if the molar ratio of the carbonic diester is excessively high,the ester exchange reaction rate tends to be decreased, and productionof a polycarbonate resin having a desired molecular weight tends to bedifficult, and in addition, an amount of the carbonic diester compoundremaining in the resin becomes so large as to produce an unpleasant odorduring the molding process or from a molded article, which isundesirable.

(Ester Exchange Catalyst)

The ester exchange catalyst used in the process for producing thepolycarbonate resin of the present invention by the melt method, may beone of catalysts generally used in producing a polycarbonate resin by anester exchange method, and is not particularly limited.

In general, examples of the catalyst include basic compounds such as analkali metal compound, an alkaline earth metal compound, a berylliumcompound, a magnesium compound, a basic boron compound, a basicphosphorus compound, a basic ammonium compound, and an amine compound.Among them, an alkali metal compound or an alkaline earth metal compoundis practically preferred. Those ester exchange catalysts may be usedalone or as a mixture of two or more of them.

The amount of use of the ester exchange catalyst is usually within arange of from 1×10⁻⁹ to 1×10⁻³ mol per 1 mol of the entire dihydroxycompound. In order to obtain a polycarbonate resin excellent in themoldability and the hue, the amount of the ester exchange catalyst is,when an alkali metal compound and/or an alkaline earth metal compound isused, preferably from 1.0×10⁻⁸ to 1×10⁻⁴ mol, more preferably from1.0×10⁻⁸ mol to 1.0×10⁻⁵ mol, particularly preferably from 1.0×10⁻⁷ molto 5.0×10⁻⁶ mol, per 1 mol of all the dihydroxy compounds. If the amountis smaller than the above lower limit, no polymerization activitynecessary to produce a polycarbonate resin having a desired molecularweight will be obtained, and if it is larger than the above upper limit,the polymer hue may be deteriorated, or the amount of branching tends tobe too large, thus leading to a decrease in the fluidity, whereby nodesired polycarbonate resin having excellent melt properties will beobtained.

Examples of the alkali metal compound include inorganic alkali metalcompounds such as hydroxides, carbonates and hydrogen carbonatecompounds of alkali metals; and organic alkali metal compounds such assalts of alkali metals with alcohols, phenols or organic carboxylicacids. Examples of the alkali metals include lithium, sodium, potassium,rubidium and cesium.

Among such alkali metal compounds, a cesium compound is preferred, andcesium carbonate, cesium hydrogen carbonate and cesium hydroxide areparticularly preferred.

Examples of the alkaline earth metal compound include inorganic alkalineearth metal compounds such as hydroxides or carbonates of alkaline earthmetals; and salts of alkaline earth metals with alcohols, phenols ororganic carboxylic acids. Examples of the alkaline earth metals includecalcium, strontium and barium.

Further, examples of the beryllium compound and magnesium compoundinclude inorganic metal compounds such as hydroxides or carbonates ofthe metals; and salts of those metals with alcohols, phenols or organiccarboxylic acids.

Examples of the basic boron compound include a sodium salt, a potassiumsalt, a lithium salt, a calcium salt, a magnesium salt, a barium saltand a strontium salt of a boron compound. Examples of the boron compoundinclude tetramethyl boron, tetraethyl boron, tetrapropyl boron,tetrabutyl boron, trimethylethyl boron, trimethylbenzyl boron,trimethylphenyl boron, triethylmethyl boron, triethylbenzyl boron,triethylphenyl boron, tributylbenzyl boron, tributylphenyl boron,tetraphenyl boron, benzyltriphenyl boron, methyltriphenyl boron andbutyltriphenyl boron.

Examples of the basic phosphorus compound include trivalent phosphoruscompounds such as triethylphosphine, tri-n-propylphosphine,triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine andtributylphosphine; and quaternary phosphonium salts derived from thosecompounds.

Examples of the basic ammonium compound include tetramethylammoniumhydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide,tetrabutylammonium hydroxide, trimethylethylammonium hydroxide,trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide,triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide,triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide,tributylphenylammonium hydroxide, tetraphenylammonium hydroxide,benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide andbutyltriphenylammonium hydroxide.

Examples of the amine compound include 4-aminopyridine, 2-aminopyridine,N,N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine,2-methoxypyridine, 4-methoxypyridine, 2-dimethylaminoimidazole,2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazoleand aminoquinoline.

(Catalyst Deactivating Agent)

In the present invention, after completion of the ester exchangereaction, a catalyst deactivating agent to neutralize and deactivate theester exchange catalyst may be added. The heat resistance and thehydrolysis resistance of a polycarbonate resin obtained by such atreatment will be improved.

Such a catalyst deactivating agent is preferably an acidic compoundhaving pKa of at most 3, such as sulfonic acid or a sulfonate, and itmay, for example, be specifically benzenesulfonic acid,p-toluenesulfonic acid, methyl benzenesulfonate, ethyl benzenesulfonate,propyl benzenesulfonate, butyl benzenesulfonate, methylp-toluenesulfonate, ethyl p-toluenesulfonate, propyl p-toluenesulfonateor butyl p-toluenesulfonate.

Among them, p-toluenesulfonic acid or butyl p-toluenesulfonate issuitably used.

The process for producing the polycarbonate resin by the melt method isconducted by preparing a material mixture melt containing the dihydroxycompound and the carbonic diester as materials (raw material preparationstep) and subjecting the material mixture melt to a multi-stagepolycondensation reaction in a molten state in the presence of an esterexchange reaction catalyst using a plurality of reaction tanks(polycondensation step). The reaction method may be any of a batchwisemethod, a continuous method and a combination of a batchwise method anda continuous method. As the reaction tanks, a plurality of verticalreaction tanks and as the case requires, at least one horizontalstirring reaction tank successive thereto are used. Usually, thesereaction tanks are connected in series to carry out the treatmentcontinuously.

After the polycondensation step, a step of terminating the reaction andevaporating and removing unreacted materials and reaction by-products inthe polycondensation reaction liquid, a step of adding a thermalstabilizer, a mold release agent, a colorant or the like, a step offorming the polycarbonate resin into a predetermined particle size, orthe like may properly be added.

Now, the respective steps in the production process will be describedbelow.

(Raw Material Preparation Step)

The dihydroxy compound and the carbonic diester compound used as rawmaterials of the polycarbonate resin are generally prepared as amaterial mixture melt using a batchwise, semibatchwise or continuousstirring tank type apparatus in an atmosphere of an inert gas such asnitrogen or argon. In the case of using bisphenol A as the dihydroxycompound and diphenyl carbonate as the carbonic diester compound, forexample, a temperature of the molten mixture is selected from a range ofusually from 120 to 180° C., preferably from 125 to 160° C.

Now, a case of using bisphenol A as the dihydroxy compound and diphenylcarbonate as the carbonic diester compound as materials will bedescribed as an example.

In this case, the ratio of the dihydroxy compound to the carbonicdiester compound is adjusted so that the carbonic diester compound is inexcess, and the carbonic diester compound is in a proportion of usuallyfrom 1.01 to 1.30 mol, preferably from 1.02 to 1.20 mol, per 1 mol ofthe dihydroxy compound.

(Polycondensation Step)

Polycondensation of an ester exchange reaction between the dihydroxycompound and the carbonic diester compound is continuously conducted bya multiple-stage method of generally at least two stages, preferablyfrom 3 to 7 stages. Specific reaction conditions of each stage are asfollows: the temperature is from 150 to 320° C., the pressure is fromordinary pressure to 0.01 Torr (1.3 Pa), and the average residence timeis from 5 to 150 minutes.

The temperature and vacuum are generally set to become higher stepwisewithin the above reaction conditions in each of the reaction tanks ofthe multi-stage method, in order to effectively discharge themonohydroxy compound such as phenol produced as a by-product with theprogress of the ester exchange reaction.

When the polycondensation step is conducted by the multi-stage method,it is preferred to provide a plurality of reaction tanks includingvertical stirring reaction tanks to increase the average molecularweight of the polycarbonate resin. The number of reaction tanks isusually from 2 to 6, preferably from 4 to 5.

Here, the reaction tanks may, for example, be stirring tank typereaction tanks, thin-film reaction tanks, centrifugal thin-filmevaporation reaction tanks, surface renewal type twin screw kneadingreaction tanks, twin screw horizontal stirring reaction tanks, wet walltype reaction tanks, porous plate type reaction tanks in whichpolycondensation proceeds during a free fall, and porous plate typereaction tanks provided with a wire, in which polycondensation proceedsduring a fall along a wire.

Examples of the type of the stirring blade in the vertical stirringreaction tanks include a turbine blade, a paddle blade, a Pfaudlerblade, an anchor blade, a FULLZONE blade (manufactured by KobelcoEco-Solutions Co., Ltd.), a SANMELLER blade (manufactured by MITSUBISHIHEAVY INDUSTRIES, LTD.), a MAXBLEND blade (manufactured by SHIMechanical & Equipment Inc.), a helicalribbon blade, and a lattice typetwisting blade (manufactured by Hitachi Plant Technologies, Ltd.).

Further, the horizontal stirring reaction tank refers to a reaction tankwith a stirring blade a revolution axis of which is horizontal(horizontal direction). Examples of the stirring blade in the horizontalreaction tank include single shaft stirring blades such as a disk typeand a paddle type, and two shaft stirring blades such as HVR, SCR andN-SCR (manufactured by MITSUBISHI HEAVY INDUSTRIES, LTD.), Bivolak(manufactured by SHI Mechanical & Equipment Inc.), and aspectacle-shaped blade and a lattice type blade (manufactured by HitachiPlant Technologies, Ltd.).

Further, the ester exchange catalyst used for the polycondensation ofthe dihydroxy compound and the carbonic diester compound may begenerally previously prepared as a solution. The concentration of thecatalyst solution is not particularly limited, and it is adjusted to anoptional concentration according to the solubility of the catalyst inthe solvent. As the solvent, acetone, an alcohol, toluene, phenol, wateror the like may properly be selected.

In a case where water is selected as the solvent of the catalyst, theproperties of the water are not particularly limited so long as kindsand concentrations of impurities contained therein are constant.Usually, distilled water, deionized water or the like is preferablyused.

<Method for Producing Polycarbonate Resin Composition>

The method for producing the polycarbonate resin composition comprisingthe polycarbonate resin (a) and the polycarbonate resin (b) of thepresent invention is not particularly limited and may, for example, be

(1) a method of melt-kneading the polycarbonate resin (a) and thepolycarbonate resin (b);

(2) a method of melt-kneading the polycarbonate resin (a) in a moltenstate and the polycarbonate resin (b) in a molten state;

(3) a method of mixing the polycarbonate resin (a) and the polycarbonateresin (b) in a solution state, or

(4) a method of dry-blending the polycarbonate resin (a) and thepolycarbonate resin (b).

Now, the respective methods will be described.

(1) Method of Melt-Kneading Polycarbonate Resin (a) and PolycarbonateResin (b)

Pellets or granules of the polycarbonate resin (a) and pellets orgranules of the polycarbonate resin (b) are melt-kneaded by using amixing apparatus such as a kneader, a twin screw extruder or a singlescrew extruder. The pellets or granules of the polycarbonate resin (a)and the pellets or granules of the polycarbonate resin (b) maypreliminarily be mixed in a solid state and then kneaded, or either oneof them is preliminarily melted in the above mixing apparatus, and theother polycarbonate resin is added and kneaded. The temperature at whichthey are kneaded is not particularly limited, and is preferably atemperature higher than Tg of the polycarbonate resin (a), morepreferably a temperature higher than Tg of the polycarbonate resin (b).Usually, it is preferably at least 240° C., more preferably at least260° C., further preferably at least 280° C. Further, it is preferablyat most 350° C., particularly preferably at most 320° C. If the kneadingtemperature is too low, mixing of the polycarbonate resin (a) and thepolycarbonate resin (b) will not be complete, and when a molded articleis produced, there may be dispersion of the hardness or the impactresistance, such being unfavorable. Further, if the kneading temperatureis too high, the color of the polycarbonate resin composition may bedeteriorated, such being unfavorable.

(2) Method of Melt-Kneading Polycarbonate Resin (a) in Molten State andPolycarbonate Resin (b) in Molten State

The polycarbonate resin (a) in a molten state and the polycarbonateresin (b) in a molten state are mixed by means of a mixing apparatussuch as a stirring tank, a static mixer, a kneader, a twin screwextruder or a single screw extruder. In this case, for example, apolycarbonate resin obtained by the melt polymerization method may beintroduced into the above mixing apparatus in a molten state withoutcooling and solidification. The mixing temperature is not particularlylimited, and is preferably at a temperature higher than the glasstransition temperature Tg(a) of the polycarbonate resin (a), morepreferably a temperature higher than the glass transition temperatureTg(b) of the polycarbonate resin (b). Usually, it is preferably at least150° C., more preferably at least 180° C., further preferably at least200° C. Further, it is preferably at most 300° C., particularlypreferably at most 250° C. If the mixing temperature is low, mixing ofthe polycarbonate resin (a) and the polycarbonate resin (b) will not becomplete, and when a molded article is produced, there may be dispersionof the hardness or the impact resistance, such being unfavorable.Further, if the mixing temperature is too high, the color of thepolycarbonate resin composition may be deteriorated, such beingunfavorable.

(3) Method of Mixing Polycarbonate Resin (a) and Polycarbonate Resin (b)in Solution State

The polycarbonate resin (a) and the polycarbonate resin (b) aredissolved in an appropriate solvent to form solutions, they are mixed ina solution state and then a polycarbonate resin composition is isolated.Such a proper solvent may, for example, be an aliphatic hydrocarbon suchas hexane or n-heptane; a chlorinated aliphatic hydrocarbon such asdichloromethane, chloroform, carbon tetrachloride, dichloroethane,trichloroethane, tetrachloroethane, dichloropropane or1,2-dichloroethylene; an aromatic hydrocarbon such as benzene, tolueneor xylene; or a substituted aromatic hydrocarbon such as nitrobenzene oracetophenone. Among them, a chlorinated hydrocarbon such asdichloromethane or chlorobenzene is suitably used. Such a solvent may beused alone or as a mixture with another solvent.

The mixing apparatus may, for example, be a stirring tank or a staticmixer. Further, the mixing temperature is not particularly limited solong as the polycarbonate resin (a) and the polycarbonate resin (b) aresoluble, and is usually at most the boiling point of the solvent used.

(4) Method of Dry-Blending Polycarbonate Resin (a) and PolycarbonateResin (b)

Pellets or granules of the polycarbonate resin (a) and pellets orgranules of the polycarbonate resin (b) are dry-blended by using atumbler, a super mixer, a Henschel mixer, a nauta mixer or the like.

Among the above methods (1) to (4), preferred are the methods (1) and(2) of melt-kneading the polycarbonate resin (a) and the polycarbonateresin (b) and the method (4) of dry-blending the polycarbonate resin (a)and the polycarbonate resin (b).

In production of the polycarbonate resin composition, in any of theabove methods, a pigment, a dye, a mold release agent, a thermalstabilizer or the like may properly be added within a range not toimpair the objects of the present invention.

(Flame Retardant)

The flame retardant used in this embodiment may, for example, be atleast one member selected from the group consisting of a metal sulfonatetype flame retardant, a halogen-containing compound type flameretardant, a phosphorus-containing compound type flame retardant and asilicon-containing compound type flame retardant. Among them, a metalsulfonate type flame retardant is preferred.

The blending amount of the flame retardant used in this embodiment isusually from 0.01 to 1 part by weight, preferably from 0.05 to 1 part byweight per 100 parts by weight of the polycarbonate.

The metal sulfonate type flame retardant may, for example, be a metalaliphatic sulfonate or a metal aromatic sulfonate. The metal of such ametal salt may, for example, be an alkali metal such as sodium, lithium,potassium, rubidium or cesium; beryllium or a magnesium such asmagnesium; or an alkaline earth metal such as calcium, strontium orbarium. The metal sulfonate may be used alone or as a mixture of two ormore.

The metal sulfonate may, for example, be a metal aromatic sulfonesulfonate or a metal perfluoroalkane sulfonate.

The metal aromatic sulfone sulfonate may, for example, be specificallysodium diphenylsulfone-3-sulfonate, potassiumdiphenylsulfone-3-sulfonate, sodium4,4′-dibromodiphenyl-sulfone-3-sulfonate, potassium4,4′-dibromodiphenyl-sulfone-3-sulfone, calcium4-chloro-4′-nitrodiphenylsulfone-3-sulfonate, disodiumdiphenylsulfone-3,3′-disulfonate or dipotassiumdiphenylsulfone-3,3′-disulfonate.

The metal perfluoroalkane sulfonate may, for example, be sodiumperfluorobutane sulfonate, potassium perfluorobutane sulfonate, sodiumperfluoromethylbutane sulfonate, potassium perfluoromethylbutanesulfonate, sodium perfluorooctane sulfonate, potassium perfluorooctanesulfonate or a tetraethylammonium salt of perfluorobutane sulfonate.

The halogen-containing compound type flame retardant may, for example,be specifically tetrabromobisphenol A, tribromophenol, brominatedaromatic triazine, a tetrabromobisphenol A epoxy oligomer, atetrabromobisphenol A epoxy polymer, decabromodiphenyl oxide,tribromoallyl ether, a tetrabromobisphenol A carbonate oligomer,ethylenebistetrabromophthalimide, decabromodiphenylethane, brominatedpolystyrene or hexabromocyclododecane.

The phosphorus-containing compound type flame retardant may, forexample, be red phosphorus, covered red phosphorus, a polyphosphatecompound, a phosphate compound or a phosphazene compound. Among them,the phosphate compound may, for example, be specifically trimethylphosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate,tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate,cresyldiphenyl phosphate, octyldiphenyl phosphate, diisopropylphenylphosphate, tris(chloroethyl)phosphate, tris(dichloropropyl)phosphate,tris(chloropropyl)phosphate, bis(2,3-dibromopropyl)-2,3-dichloropropylphosphate, tris(2,3-dibromopropyl)phosphate, bis(chloropropyl)monooctylphosphate, bisphenol A bisphosphate, hydroquinone bisphosphate, resorcinbisphosphate or trioxybenzene triphosphate.

The silicon-containing compound type flame retardant may, for example,be silicone varnish, a silicone resin wherein substituents bonded tosilicon atoms are an aromatic hydrocarbon group and an aliphatichydrocarbon group having at least 2 carbon atoms, a silicone compoundhaving a branched main chain and having an aromatic group in the organicfunctional group contained, a silicone powder having apolydiorganosiloxane polymer which may have functional groups supportedon the surface of a silica powder, or anorganopolysiloxane-polycarbonate copolymer.

The polycarbonate resin composition to which this embodiment isapplicable, which comprises a combination of the polycarbonate resinhaving structural units represented by the above formula (1) and theflame retardant, has flame retardancy improved as compared with a resincomposition using a polycarbonate resin obtainable by using bisphenol Aas a raw material monomer (hereinafter referred to as “A-PC”) forexample.

The reason why the flame retardancy of the polycarbonate resincomposition to which this embodiment is applicable is improved is notclearly understood, but is considered to be as follows, with referenceto a case of using a polycarbonate resin obtained by using2,2-bis(3-methyl-4-hydroxyphenyl)propane which is an aromatic dihydroxycompound as the raw material monomer (hereinafter referred to as “C-PC”)as the polycarbonate resin component, as an example.

That is, C-PC has a low thermal decomposition starting temperature ascompared with A-PC and is likely to be decomposed. Thus, C-PC is quicklydecomposed and graphitized, thus forming a heat insulating layer (char),whereby flame retardancy is easily attained. The low thermaldecomposition starting temperature of C-PC as compared with A-PC isinfluenced by the difference in the structure of the bisphenol structurethat “the 3-position of each of the two benzene rings is substituted bya methyl group”. Particularly in a case where C-PC is produced by theabove-described melt method, when the polymerization reaction proceedsin a molten state at high temperature and at high shear strength, abranch is likely to form from the 3-position of each of the phenyl ringsof the bisphenol compound. Accordingly, the flame retardancy is improvedsuch that in a flame test, flaming drips are suppressed.

Further, C-PC has a lowered packing density of molecular chains ascompared with A-PC and has molecular chains which are rigid and hardlymove, and thus the molded article of resin tends to have a low shrinkageand a low linear expansion coefficient. Thus, high dimensional stabilityof the molded article of resin is expected.

The polycarbonate resin composition to which this embodiment isapplicable, which has such properties, is suitable for resin members forwhich high dimensional accuracy is required, such as chassis forprecision instruments such as cellular phones and PCs; housing for homeelectric appliances such as TVs; screen films; exterior members of amulticolor molded article of resin of two or more colors, such asglazing; and multilayered extruded articles having at least two surfacelayers of building materials such as carports, agricultural greenhousesand acoustic insulation boards.

Further, the polycarbonate resin composition to which this embodiment isapplicable, with which a molded article of resin having high hardnessand improved flame retardancy can be obtained, is suitable forapplications of e.g. molded articles of resin related to illuminationsuch as LED, such as lamp lenses, protective covers and diffusers;lenses for glasses, vending machine buttons, and keys of e.g. mobiledevices.

With the polycarbonate resin composition to which this embodiment isapplicable, various additives are blended as the case requires. Theadditives may, for example, be a stabilizer, an ultraviolet absorber, amold release agent, a colorant, an antistatic agent, a thermoplasticresin, a thermoplastic elastomer, glass fibers, glass flakes, glassbeads, carbon fibers, Wollastonite, calcium silicate and aluminum boratewhiskers.

The method of mixing the polycarbonate resin and the flame retardant andthe additives or the like blended as the case requires is notparticularly limited. In this embodiment, for example, a method ofmixing the polycarbonate resin in a solid state such as pellets or apowder with the flame retardant and the like, followed by kneading e.g.by an extruder, a method of mixing the polycarbonate resin in a moltenstate and the flame retardant and the like, and a method of adding theflame retardant and the like during the polymerization reaction of theraw material monomer by the melt method or the interfacial method, orwhen the polymerization reaction is completed, may be mentioned.

<Method for Producing Molded Article of Polycarbonate Resin>

The method for producing the molded article of polycarbonate resin ofthe present invention is not particularly limited, and it is suitable toemploy a production method using the polycarbonate resin (a) and thepolycarbonate resin (b) each having a specific viscosity averagemolecular weight, so as to improve the surface hardness of the moldedarticle of polycarbonate resin.

That is, the production method of the present invention is a method forproducing the molded article of polycarbonate resin, comprising at leasta polycarbonate resin (a) having structural units (a) derived from acompound represented by the above formula (1) and a polycarbonate resin(b) having structural units (b) different from the structural units (a),which comprises melt-kneading or dry-blending the polycarbonate resin(a) and the polycarbonate resin (b), followed by molding, wherein theviscosity average molecular weight (Mv(a)) of the polycarbonate resin(a) is higher than the viscosity average molecular weight (Mv(b)) of thepolycarbonate resin (b).

<Method for Producing Molded Article>

To produce a molded article of resin from the polycarbonate resincomposition of the present invention, a conventional extruder orinjection molding machine is used. The molded article of polycarbonateresin of the present invention is preferably molded by injection moldingusing an injection molding machine, in view of advantages such thatmolded articles of polycarbonate resins having a complicated shape canbe molded with a high cycle rate.

The barrel temperature in molding is preferably a temperature higherthan Tg(a), more preferably a temperature higher than Tg(b). Usually, itis preferably at least 200° C., more preferably at least 250° C., mostpreferably at least 280° C. Further, it is preferably at most 350° C.,particularly preferably at most 320° C. If the molding temperature istoo low, the melt viscosity tends to be high, the fluidity tends to bedecreased, the moldability may be decreased, the effect of improving thesurface hardness may be decreased, and the surface hardness of theobtainable resin composition may be decreased. If the moldingtemperature is too high, the polycarbonate resin will be colored,whereby the color of the polycarbonate resin composition is alsodeteriorated in some cases, such being unfavorable.

<Method for Producing Injection-Molded Article>

To produce an injection-molded article from the polycarbonate resincomposition of the present invention, a conventional injection moldingmachine is used.

When an injection molding machine or the like is used, the moldtemperature is preferably a temperature lower than Tg(b), morepreferably a temperature lower than Tg(a). Usually, it is preferably atmost 150° C., more preferably at most 120° C., most preferably at most100° C. Further, it is preferably at least 30° C., particularlypreferably at least 50° C. If the mold temperature is too high, thecooling time at the time of molding is required to be long, whereby thecycle of production of the molded article tends to be long, thusdecreasing the productivity in some cases. If the mold temperature istoo low, the melt viscosity of the resin composition tends to be toohigh, whereby no uniform molded article may be obtained, and problemsmay arise such that the molded article surface is non-uniform, suchbeing unfavorable.

<Method for Producing Extruded Article>

To produce an extruded article from the polycarbonate resin compositionof the present invention, a conventional extruder is used. The extruderis usually provided with a T-die, a round die or the like, and extrudedarticles of various shapes can be obtained. The shape of the obtainedextruded article may, for example, be a sheet, film, plate, tube or pipeshape. Among them, a sheet or a film is preferred.

In order to improve the adhesion, coating properties, printingproperties and the like of the extruded article of the polycarbonateresin composition of the present invention, a hard coating layer may belaminated on both sides or one side of the extruded article, a weatherresistance and/or scratch resistance improving film may beheat-laminated on both sides or one side of the extruded article, orembossing or translucent or opaque treatment may be applied to thesurface.

Further, when injection molding or extrusion is carried out, a pigment,a dye, a mold release agent, a thermal stabilizer or the like mayproperly be added within a range not to impair the objects of thepresent invention.

The above-mentioned molded article may be used in various fields ofbuildings, vehicles, electric/electronic devices, machines and others.

<Flame Retardancy of Molded Article of Polycarbonate Resin>

A molded article of polycarbonate resin is prepared by using thepolycarbonate resin composition to which this embodiment is applicableas described above. The method of molding the molded article ofpolycarbonate resin is not particularly limited, and for example, amolding method using a conventional molding machine such as an injectionmolding machine may be mentioned. The molded article of polycarbonateresin to which this embodiment is applicable has a decrease in thesurface hardness and the transparency suppressed and has favorable flameretardancy, as compared with a case of using, for example, apolycarbonate resin obtainable by using e.g. bisphenol A having nosubstituent on the phenyl ring as a monomer.

Specifically, the molded article of polycarbonate resin to which thisembodiment is applicable, with respect to the flame retardancy,preferably satisfies the classification V-0 in a flammability test ofUL94 with respect to a test specimen having a thickness of at most 2 mm.With respect to the transparency, the haze is preferably at most 1.0with respect to a test specimen having a thickness of 3 mm in accordancewith JIS K7136.

EXAMPLES

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is not limited to the following Examples.

Physical properties of polycarbonate resins and polycarbonate resincompositions used in Examples were evaluated by the following methods.

(1) Pencil Hardness of Molded Article

Using an injection molding machine J50E2 (manufactured by Japan SteelWorks, Ltd.), a plate (molded article) of a polycarbonate resin or aplate (molded article) of a polycarbonate resin composition of 60 mm×60mm×3 mm in thickness was molded by injection-molding under conditions ofa barrel temperature of 280° C. and a mold temperature of 90° C. Withrespect to each molded article, in accordance with ISO 15184 using apencil hardness tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.),the pencil hardness measured at a load of 750 g was obtained.

(2) Melt Viscosity

It was measured with respect to a polycarbonate resin or a polycarbonateresin composition dried at 120° C. for 5 hours by using a capillaryrheometer “Capirograph 1C” (manufactured by Toyo Seiki Seisaku-sho,Ltd.) equipped with a die of 1 mm in diameter×30 mm at 280° C. at ashear rate of 122 (sec⁻¹). If this melt viscosity is too high, thefluidity tends to be low, and the moldability will be deteriorated, andaccordingly it is required to be within an appropriate range.

(3) Intrinsic Viscosity [η]

A polycarbonate resin or a polycarbonate resin composition was dissolvedin methylene chloride (concentration: 6.0 g/L (liter)) to form asolution. Then, with respect to this solution, the intrinsic viscositywas measured by an Ubbelohde viscosity tube at a temperature of 20° C.

(4) Glass Transition Temperature (Tg)

Using a differential scanning calorimeter DSC6220 (manufactured by SeikoInstruments Inc.), about 10 mg of a polycarbonate resin sample washeated at a heating rate of 20° C./min and the calorie is measured, andin accordance with JIS K7121, an extrapolated glass transition startingtemperature which is a temperature at the intersection of a lineobtained by extending the base line on the low temperature side to thehigh temperature side and a tangent drawn at a point where the gradientof a curve of the stepwise change portion of glass transition wasmaximum, was obtained. This extrapolated glass transition temperaturewas regarded as the glass transition temperature (Tg).

(5) Viscosity Average Molecular Weight (Mv)

A polycarbonate resin was dissolved in methylene chloride(concentration: 6.0 g/L), the specific viscosity (ηsp) at 20° C. wasmeasured by using an Ubbelohde viscosity tube, and the viscosity averagemolecular weight (Mv) was calculated in accordance with the followingformula.

ηsp/C=[η](1+0.28ηsp)

[η]=1.23×10⁻⁴ Mv ^(0.83)

(6) Yellowness Index (YI) of Polycarbonate Resin or Polycarbonate ResinComposition

Using the molded article molded in the above (1), the yellowness index(YI) was measured by a spectral colorimeter CM-3700d (manufactured byKONICA MINOLTA HOLDINGS, INC.). The smaller the value, the brighter thecolor and the better the transparency.

(7) Charpy Impact Strength of Polycarbonate Resin or Polycarbonate ResinComposition

Using an injection molding machine J50E2 (manufactured by Japan SteelWorks, Ltd.), a polycarbonate resin or a polycarbonate resin compositionwas molded to obtain a molded specimen under conditions of a barreltemperature of 280° C. and a mold temperature of 90° C. Using thismolded specimen, in accordance with JIS K7111, the impact strength wasmeasured with a notch of 0.25 mmR.

(8) Pencil Hardness of Extruded Article

A polycarbonate resin or a polycarbonate resin composition having athickness of 240 μm and a width of 140±5 mm was extruded into a sheet(extruded article) by using a 25 mmφ single screw extruder (manufacturedby ISUZU KAKOKI K.K.) under conditions of a barrel temperature of 280°C. and a roll temperature of 90° C. With respect to this extrudedarticle, in accordance with ISO 15184, using a pencil hardness tester(manufactured by Toyo Seiki Seisaku-sho, Ltd.), the pencil hardnessmeasured at a load of 750 g was obtained.

(9) Yellowness Index (YI) of Extruded Article

With respect to the extruded article molded in the above (7), theyellowness index (YI) was measured by a spectral colorimeter CM-3700d(manufactured by KONICA MINOLTA HOLDINGS, INC.). The smaller the value,the brighter the color and the better the transparency.

(10) Pencil Hardness of Polycarbonate Resin Cast Article

In a case where the molecular weight of the polycarbonate resin is lowand a molded article for evaluation of the pencil hardness cannot bemolded by the above-described method (1), an evaluation sample wasprepared as follows.

100 g of a polycarbonate resin was added in a glass vessel equipped witha stirring blade, followed by replacement with nitrogen, and thepressure in the glass vessel was maintained at 101.3 kPa (760 Torr) bythe absolute pressure. The glass vessel was immersed in an oil bathheated at 280° C. to melt the polycarbonate resin. After thepolycarbonate resin was uniformly melted, the molten polycarbonate resinwas taken out from the glass vessel into a stainless steel vat in athickness of about 3 mm and cooled to room temperature. With respect tothe cooled polycarbonate resin, in accordance with ISO 15184, using apencil hardness tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.),the pencil hardness at a load of 750 g was measured.

(11) Content [S] of Structural Units (a) on the Surface of MoldedArticle of Polycarbonate Resin.

A polycarbonate resin or a polycarbonate resin composition was moldedinto a molded article of polycarbonate resin of 60 mm×60 mm×3 mm inthickness by an injection molding machine J50E2 (manufactured by JapanSteel Works, Ltd.) under conditions of a barrel temperature of 280° C.and a mold temperature of 90° C. Then, the molded article ofpolycarbonate resin was immersed in methylene chloride (about 400 g) atroom temperature (25° C.). Five seconds after the start of immersion,the molded article of polycarbonate resin was taken out from methylenechloride to obtain a methylene chloride solution. By means of anevaporator, methylene chloride was removed under reduced pressure fromthe methylene chloride solution to obtain a residue. The residue wasdissolved in deuterochloroform, and the solution was subjected tomeasurement by ¹H-NMR method. From the signal intensity of structuralunits (a) and signal intensities of other structural units in theobtained ¹H-NMR spectrum, the content [S] (wt %) of the structural units(a) on the surface of the molded article of polycarbonate resin wascalculated.

(12) Content [T] of Structural Units (a) in the Entire Molded Article ofPolycarbonate Resin

In the same manner as the above (6), a molded article of polycarbonateresin of 60 mm×60 mm×3 mm in thickness was molded. Then, the moldedarticle of polycarbonate resin was immersed in methylene chloride (about400 g) at room temperature (25° C.) and was completely dissolved, toobtain a methylene chloride solution. About 50 g of the methylenechloride solution was taken, methylene chloride was removed underreduced pressure by means of an evaporator to obtain a residue. Theresidue was dissolved in deuterochloroform, and the solution wassubjected to measurement by ¹H-NMR method. From the signal intensity ofstructural units (a) and the signal intensities of other structuralunits in the obtained ¹H-NMR spectrum, the content [T] (wt %) of thestructural units (a) in the entire molded article was calculated.

The polycarbonate resins used in Examples are shown below.

A. Polycarbonate Resin: (1) Polycarbonate Resin (a): Reference Example 1Preparation of PC(a1)

To 37.6 kg (about 147 mol) of 2,2-bis(4-hydroxy-3-methylphenyl)propane(hereinafter sometimes referred to as “BPC”) (manufactured by HONSHUCHEMICAL INDUSTRY CO., LTD.) and 32.2 kg (about 150 mol) of diphenylcarbonate (DPC), an aqueous solution of cesium carbonate was added sothat cesium carbonate would be 2 μmol per 1 mol of BPC to prepare amixture. Then, the mixture was charged into a first reactor having aninternal volume of 200 L equipped with a stirring machine, a heat mediumjacket, a vacuum pump and a reflux condenser.

Then, an operation of reducing the pressure in the first reactor to 1.33kPa (10 Torr) and then recovering it to the atmospheric pressure bynitrogen was repeatedly carried out five times, and then the interior inthe first reactor was replaced with nitrogen. After replacement withnitrogen, a heat medium at a temperature of 230° C. was passed throughthe heat medium jacket to gradually increase the internal temperature inthe first reactor thereby to dissolve the mixture. Then, the stirringmachine was rotated at 300 rpm, and the temperature in the heat mediumjacket was controlled to keep the internal temperature of the firstreactor at 220° C. Then, while phenol formed as a by-product by anoligomerization reaction of BPC and DPC conducted in the interior of thefirst reactor was distilled off, the pressure in the first reactor wasreduced from 101.3 kPa (760 Torr) to 13.3 kPa (100 Torr) by the absolutepressure over a period of 40 minutes.

Then, the pressure in the first reactor was maintained at 13.3 kPa, andwhile phenol was further distilled off, an ester exchange reaction wascarried out for 80 minutes. Then, the polycarbonate resin was withdrawnfrom the bottom of the tank.

The obtained polycarbonate resin (PC(a1) had a viscosity averagemolecular weight of 1,900, and a glass transition temperature (Tg) of atmost 100° C.

Reference Example 2 Preparation of PC(a2)

In the same manner as in Reference Example 1, an ester exchange reactionin the first reactor was carried out for 80 minutes. Then, the pressurein the system was recovered to 101.3 kPa by the absolute pressure withnitrogen, and then the pressure was elevated to 0.2 MPa by the gaugepressure, and by means of a transfer pipe preliminarily heated to atleast 200° C., the oligomer in the first reactor was pumped to a secondreactor. The second reactor had an internal volume of 200 L, wasequipped with a stirring machine, a heat medium jacket, a vacuum pumpand a reflux condenser, and had the internal pressure and the internaltemperature controlled to the atmospheric pressure and 240° C.

Then, the oligomer pumped to the second reactor was stirred at 38 rpm,the internal temperature was raised by the heat medium jacket, and thepressure in the second reactor was reduced from 101.3 kPa to 13.3 kPa bythe absolute pressure over a period of 40 minutes. Then, thetemperature-raising was continued, and the internal pressure was reducedfrom 13.3 kPa to 399 Pa (3 Torr) by the absolute pressure further over aperiod of 40 minutes, and distilled phenol was removed out of thesystem. Further, the temperature raising was continued, and after theabsolute pressure in the second reactor reached 70 Pa (about 0.5 Torr),the pressure was maintained at 70 Pa, and a polycondensation reactionwas carried out. The final internal temperature in the second reactorwas 285° C. When the stirring machine of the second reactor achieved apreliminarily described predetermined stirring power, thepolycondensation reaction was completed.

The obtained polycarbonate resin (PC(a2) had a viscosity averagemolecular weight of 6,700 and a glass transition temperature (Tg) of101° C.

Reference Examples 3 and 4 Preparation of PC(a3) and PC(a4)

A reaction was carried out in accordance with Reference Example 2 exceptthat the preliminarily determined stirring power of the stirring machineof the second reactor at the time of completion was changed. Then, thepressure in the second reactor was recovered to 101.3 kPa by theabsolute pressure with nitrogen, and then the pressure was elevated to0.2 MPa by the gauge pressure, the polycarbonate resin was withdrawnfrom the bottom of the second reactor in the form of strands, which werepelletized by using a rotary cutter while cooling in a water tank.

That is, by changing the preliminarily determined stirring power of thestirring machine of the second reactor at the time of completion, apolycarbonate resin (PC(a3)) and a polycarbonate resin (PC(a4)) wererespectively obtained. The viscosity average molecular weight, the glasstransition temperature (Tg) and the pencil hardness are as shown inTable 1.

Reference Example 5 Preparation of PC(a5)

The same operation as in Reference Example 3 was carried out except that43.5 kg of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane (hereinaftersometimes referred to as “Bis-OCZ”) (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) was used instead of BPC as the material dihydroxycompound, and the aqueous solution of cesium carbonate was added so thatcesium carbonate would be 5 μmol per 1 mol of Bis-OCZ. Of the obtainedpolycarbonate resin (PC(a5)), the viscosity average molecular weight was10,200, the glass transition temperature (Tg) was 132° C., and thepencil hardness was 3H.

Reference Example 6 Preparation of PC(a6)

100 Parts by weight of Bis-OCZ (manufactured by HONSHU CHEMICAL INDUSTRYCO., LTD.), 272.1 parts by weight of a 25 wt % sodium hydroxide (NaOH)aqueous solution and 411.3 parts by weight of water, in the presence of0.339 part by weight of hydrosulfite, were dissolved at 60° C. and thencooled to room temperature to obtain a Bis-OCZ aqueous solution. ThisBis-OCZ aqueous solution in a rate of 8.87 kg/hour (the amount per onehour, the same applies hereinafter) and methylene chloride in a rate of4.37 kg/hour were introduced into a 1.8 L glass first reactor equippedwith a reflux condenser, a stirring machine and a coolant jacket, andwere brought into contact with phosgene at room temperature separatelysupplied thereto in a rate of 0.775 kg/hour. The reaction temperature atthis time reached 38° C. Then, the reaction liquid/reaction gas mixturewas introduced into a subsequent second reactor (1.8 L) having the sameshape as the first reactor by means of an overflow tube attached to thereactor and reacted. Into the second reactor, separately,p-t-butylphenol (16 wt % methylene chloride solution) as a molecularweight adjusting agent was introduced in a rate of 0.037 kg/hour. Then,the reaction liquid/reaction gas mixture was introduced into anoligomerization tank (4.5 L) having the same shape as the first reactorthrough an overflow tube attached to the second reactor. Into theoligomerization tank, separately, a 2 wt % trimethylamine aqueoussolution as a catalyst was introduced in a rate of 0.016 kg/hour(0.00083 mol per 1 mol of Bis-OCZ). Then, the oligomerized emulsion thusobtained was further introduced into a separation tank (settler) havingan internal volume of 5.4 L to separate an aqueous phase and an oilphase, thereby to obtain a methylene chloride solution of the oligomer.

2.44 kg of the above methylene chloride solution of the oligomer wascharged into a reaction tank having an internal volume of 6.8 L equippedwith a paddle blade, and 2.60 kg of methylene chloride for dilution wasadded, and further 0.245 kg of a 25 wt % sodium hydroxide aqueoussolution, 0.953 kg of water and 8.39 g of a 2 wt % triethylamine aqueoussolution were added, followed by stirring at 10° C. to carry out apolycondensation reaction for 180 minutes.

3.12 kg of the polycondensation reaction liquid was charged into areaction tank having an internal volume of 5.4 L equipped with a paddleblade, and 2.54 kg of methylene chloride and 0.575 kg of water wereadded, followed by stirring for 15 minutes, and then stirring wasstopped, and an aqueous phase and an organic phase were separated. Tothe separated organic phase, 1.16 kg of 0.1 N hydrochloric acid wasadded, followed by stirring for 15 minutes, to extract triethylamine andan alkali component remaining in a small amount, and then stirring wasstopped, and an aqueous phase and an organic phase were separated.Further, to the separated organic phase, 1.16 kg of pure water wasadded, followed by stirring for 15 minutes, and then stirring wasstopped, and an aqueous phase and an organic phase were separated. Thisoperation was repeated three times. The obtained polycarbonate solutionwas transferred (fed) into warm water of from 60 to 75° C. to powder thepolycarbonate resin, followed by drying to obtain a powderypolycarbonate resin (PC(a6)). The viscosity average molecular weight,the glass transition temperature (Tg) and the pencil hardness are asshown in Table 1.

Reference Example 2-1 PC(a2-1)

100 Parts by weight of Bis-OCZ as the material dihydroxy compound, 272.1parts by weight of a 25 wt % sodium hydroxide (NaOH) aqueous solutionand 411.3 parts by weight of water, in the presence of 0.339 part byweight of hydrosulfite, were dissolved at 60° C. and then cooled to roomtemperature to obtain a Bis-OCZ aqueous solution. This Bis-OCZ aqueoussolution in a rate of 8.87 kg/hour and methylene chloride in a rate of4.37 kg/hour were introduced into a 1.8 L glass first reactor equippedwith a reflux condenser, a stirring machine and a coolant jacket, andbrought into contact with phosgene at room temperature separatelysupplied thereto in a rate of 0.775 kg/hour. The reaction temperature atthis time reached 38° C. Then, the reaction liquid/reaction gas mixturewas introduced into a subsequent second reactor (1.8 L) having the sameshape as the first reactor through an overflow tube attached to thereactor, and reacted. To the second reactor, separately, p-t-butylphenol(16 wt % methylene chloride solution) as a molecular weight adjustingagent was introduced in a rate of 0.037 kg/hour. Then, the reactionliquid/reaction gas mixture was introduced into an oligomerization tank(4.5 L) having the same shape as the first reactor through an overflowtube attached to the second reactor. To the oligomerization tank,separately, a 2 wt % trimethylamine aqueous solution as a catalyst wasintroduced in a rate of 0.016 kg/hour (0.00083 mol per 1 mol ofBis-OCZ). Then, the oligomerized emulsion thus obtained was furtherintroduced into a separation tank (settler) having an internal volume of5.4 L to separate an aqueous phase and an oil phase, thereby to obtain amethylene chloride solution of the oligomer.

2.44 kg of the above methylene chloride solution of the oligomer wascharged into a reaction tank having an internal volume of 6.8 L equippedwith a paddle blade, and 2.60 kg of methylene chloride for dilution wasadded, and further 0.245 kg of a 25 wt % sodium hydroxide aqueoussolution, 0.953 kg of water, 8.39 g of a 2 wt % triethylamine aqueoussolution and 25.8 g of p-t-butylphenol (16 wt % methylene chloridesolution) as a molecular weight adjusting agent were added, followed bystirring at 10° C. to carry out a polycondensation reaction for 180minutes.

3.12 kg of the above polycondensation reaction liquid was charged into areaction tank having an internal volume of 5.4 L equipped with a paddleblade, and 2.54 kg of methylene chloride and 0.575 kg of water wereadded, followed by stirring for 15 minutes, and then stirring wasstopped to separate an aqueous phase and an organic phase. To theseparated organic phase, 1.16 kg of 0.1 N hydrochloric acid was added,followed by stirring for 15 minutes, to extract triethylamine and analkali component remaining in a small amount, and then stirring wasstopped to separate an aqueous phase and an organic phase. Further, tothe separated organic phase, 1.16 kg of pure water was added, followedby stirring for 15 minutes, and then stirring was stopped and an aqueousphase and an organic phase were separated. This operation was repeatedthree times. The obtained polycarbonate solution was transferred to warmwater of from 60 to 75° C., to powder the polycarbonate resin, followedby drying to obtain a powdery polycarbonate resin. The intrinsicviscosity was 0.23, and the pencil hardness was 3H.

Reference Example 2-2 Preparation of PC(a2-2)

To 43.5 kg (about 147 mol) of Bis-OCZ (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) as the material dihydroxy carbonate and 32.2 kg(about 150 mol) of diphenyl carbonate (DPC), an aqueous solution ofcesium carbonate was added so that cesium carbonate would be 5 μmol per1 mol of the dihydroxy compound to prepare a mixture. Then, the mixturewas charged into a first reactor having an internal capacity of 200 Lequipped with a stirring machine, a heat medium jacket, a vacuum pumpand a reflux condenser.

Then, an operation of reducing the pressure in the first reactor to 1.33kPa (10 Torr) and then recovering it to the atmospheric pressure withnitrogen was repeatedly carried out five times, and the interior in thefirst reactor was replaced with nitrogen. After replacement withnitrogen, a heat medium at a temperature of 230° C. was passed throughthe heat medium jacket to gradually increase the internal temperature inthe first reactor to dissolve the mixture. Then, the stirring machinewas rotated at 300 rpm, and the temperature in the heat medium jacketwas controlled to maintain the internal temperature of the first reactorat 220° C. Then, while phenol formed as a by-product by anoligomerization reaction of Bis-OCZ and DPC carried out in the interiorof the first reactor was distilled off, the pressure in the firstreactor was reduced from 101.3 kPa (760 Torr) to 13.3 kPa (100 Torr) bythe absolute pressure over a period of 40 minutes.

Then, the pressure in the first reactor was maintained at 13.3 kPa, andwhile phenol was further distilled off, an ester exchange reaction wascarried out for 80 minutes. Then, the polycarbonate resin was withdrawnfrom the bottom of the tank.

The obtained polycarbonate resin had an intrinsic viscosity of 0.07.

Reference Example 2-3 Preparation of PC(a2-3)

In the same manner as in Reference Example 2-2, an ester exchangereaction in the first reactor was carried out for 80 minutes. Then, thepressure in the system was recovered to 101.3 kPa by the absolutepressure with nitrogen, and then the pressure was elevated to 0.2 MPa bythe gauge pressure, and the oligomer in the first reactor was pumped toa second reactor by means of a transfer pipe preliminarily heated to atleast 200° C. The second reactor had an internal volume of 200 L, wasprovided with a stirring machine, a heat medium jacket, a vacuum pumpand a reflux condenser, and had the internal pressure and the internaltemperature controlled to be the atmospheric pressure and 240° C.

Then, the oligomer pumped to the second reactor was stirred at 38 rpm,the internal temperature was raised by the heat medium jacket, and thepressure in the second reactor was reduced from 101.3 kPa to 13.3 kPa bythe absolute pressure over a period of 40 minutes. Then, the temperatureraising was continued, and the internal pressure was reduced from 13.3kPa to 399 Pa (3 Torr) by the absolute pressure further over a period of40 minutes, and the distilled phenol was removed out of the system.Further, the temperature raising was continued, and after the absolutepressure in the second reactor reached 70 Pa (about 0.5 Torr), apressure of 70 Pa was maintained, and a polycondensation reaction wascarried out. The final internal temperature in the second reactor was285° C. When the stirring machine of the second reactor achieved apreliminarily determined stirring power, the polycondensation reactionwas completed.

The obtained polycarbonate resin had an intrinsic viscosity of 0.26 anda pencil hardness of 3H.

Reference Example 2-4 Preparation of PC(a2-4)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 2-3 except that to 37.6 kg (about 147 mol) of BPC (manufacturedby HONSHU CHEMICAL INDUSTRY CO., LTD.) as the material dihydroxycompound and 32.2 kg (about 150 mol) of diphenyl carbonate (DPC), anaqueous solution of cesium carbonate was added in an amount of 2 μmolper 1 mol of the dihydroxy compound to prepare a mixture. The obtainedpolycarbonate resin had an intrinsic viscosity of 0.06.

Reference Example 2-5 Preparation of PC(a2-5)

360 Parts by weight of BPC (manufactured by HONSHU CHEMICAL INDUSTRYCO., LTD.), 585.1 parts by weight of a 25 wt % sodium hydroxide (NaOH)aqueous solution and 1,721.5 parts by weight of water, in the presenceof 0.41 part by weight of hydrosulfite, were dissolved at 40° C. andthen cooled to 20° C. to obtain a BPC aqueous solution. This BPC aqueoussolution in a rate of 8.87 kg/hour and methylene chloride in a rate of4.50 kg/hour were introduced into a 1.8 L glass first reactor equippedwith a reflux condenser, a stirring machine and a coolant jacket, andbrought into contact with phosgene at room temperature separatelysupplied thereto in a rate of 0.672 kg/hour. The reaction temperature atthis time reached 35° C. Then, the reaction liquid/reaction gas mixturewas introduced into a subsequent second reactor (1.8 L) having the sameshape as the first reactor through an overflow tube attached to thereactor, and reacted. To the second reactor, separately, p-t-butylphenol(8 wt % methylene chloride solution) as a molecular weight adjustingagent was introduced in a rate of 0.097 kg/hour. Then, the reactionliquid/reaction gas mixture was introduced into an oligomerization tank(4.5 L) having the same shape as the first reactor through an overflowtube attached to the second reactor. To the oligomerization tank,separately, a 2 wt % trimethylamine aqueous solution as a catalyst wasintroduced in a rate of 0.020 kg/hour. Then, the oligomerized emulsionthus obtained was further introduced into a separation tank (settler)having an internal volume of 5.4 L to separate an aqueous phase and anoil phase, thereby to obtain a methylene chloride solution of theoligomer.

2.60 kg of the above methylene chloride solution of the oligomer wascharged into a reaction tank having an internal volume of 6.8 L equippedwith a paddle blade, and 2.44 kg of methylene chloride for dilution wasadded, and further 0.278 kg of a 25 wt % sodium hydroxide aqueoussolution, 0.927 kg of water, 8.37 g of a 2 wt % triethylamine aqueoussolution and 25.8 g of p-t-butylphenol (8 wt % methylene chloridesolution) were added, followed by stirring at 10° C. to carry out apolycondensation reaction for 180 minutes.

3.12 kg of the above polycondensation reaction liquid was charged into areaction tank having an internal volume of 5.4 L equipped with a paddleblade, and 2.54 kg of methylene chloride and 0.575 kg of water wereadded, followed by stirring for 15 minutes, and then stirring wasstopped to separate an aqueous phase and an organic phase. To theseparated organic phase, 1.16 kg of 0.1 N hydrochloric acid was added,followed by stirring for 15 minutes, to extract triethylamine and analkali component remaining in a small amount, and then stirring wasstopped to separate an aqueous phase and an organic phase. Further, tothe separated organic phase, 1.16 kg of pure water was added, followedby stirring for 15 minutes, and then stirring was stopped and an aqueousphase and an organic phase were separated. This operation was repeatedthree times. The obtained polycarbonate solution was transferred to warmwater of from 60 to 75° C., to powder the polycarbonate resin, followedby drying to obtain a powdery polycarbonate resin. The obtainedpolycarbonate resin had an intrinsic viscosity of 0.25 and a pencilhardness of 2H.

Reference Example 2-6 Preparation of PC(a2-6)

In the same manner as in Reference Example 2-4, an ester exchangereaction in the first reactor was carried out for 80 minutes. Then, thepressure in the system was recovered to 101.3 kPa by the absolutepressure with nitrogen, and then the pressure was elevated to 0.2 MPa bythe gauge pressure, and the oligomer in the first reactor was pumped toa second reactor by means of a transfer pipe preliminarily heated to atleast 200° C. The second reactor had an internal volume of 200 L, wasprovided with a stirring machine, a heat medium jacket, a vacuum pumpand a reflux condenser, and had the internal pressure and the internaltemperature controlled to be the atmospheric pressure and 240° C.

Then, the oligomer pumped to the second reactor was stirred at 38 rpm,the internal temperature was raised by the heat medium jacket, and thepressure in the second reactor was reduced from 101.3 kPa to 13.3 kPa bythe absolute pressure over a period of 40 minutes. Then, the temperatureraising was continued, and the internal pressure was reduced from 13.3kPa to 399 Pa (3 Torr) by the absolute pressure further over a period of40 minutes, and the distilled phenol was removed out of the system.Further, the temperature raising was continued, and after the absolutepressure in the second reactor reached 70 Pa (about 0.5 Torr), apressure of 70 Pa was maintained, and a polycondensation reaction wascarried out. The final internal temperature in the second reactor was285° C. When the stirring machine of the second reactor achieved apreliminarily determined stirring power, the polycondensation reactionwas completed. The obtained polycarbonate resin had an intrinsicviscosity of 0.18 and a pencil hardness of 2H.

Reference Example 2-7 Preparation of PC(a2-7)

A reaction was carried out in accordance with Reference Example 2-6except that the preliminarily determined stirring power of the stirringmachine of the second reactor at the time of completion was changed.Then, the pressure in the second reactor was recovered to 101.3 kPa bythe absolute pressure with nitrogen, and the pressure was elevated to0.2 MPa by the gauge pressure, and the polycarbonate resin was withdrawnfrom the bottom of the second reactor in the form of strands, which werepelletized by using a rotary cutter while cooling in a water tank. Theobtained polycarbonate resin had an intrinsic viscosity of 0.69 and apencil hardness of 2H.

Reference Example 2-8 Preparation of PC(a2-8)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 2-5 except that when the methylene chloride solution was chargedinto the reaction tank having an internal volume of 6.8 L equipped witha paddle blade, p-t-butylphenol as a molecular weight adjusting agentwas not introduced. The intrinsic viscosity was 0.97, and the pencilhardness was 2H.

Reference Example 2-9 Preparation of PC(a2-9)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 2-1 except that when the methylene chloride solution was chargedinto the reaction tank having an internal volume of 6.8 L equipped witha paddle blade, no molecular weight adjusting agent was added. Theintrinsic viscosity was 0.98, and the pencil hardness was 3H.

Reference Example 2-10 Preparation of PC(a2-10): Preparation ofCDOBC/BPA (50/50 wt %) Copolymer (Melt Method)

The same operation as in Reference Example 2-7 was carried out exceptthat 20.62 kg (about 90 mol) of BPA and 20.62 kg (about 54 mol) of CDOBC(manufactured by Taoka Chemical Co., Ltd.) were used as the dihydroxycompounds, and the aqueous solution of cesium carbonate was added sothat cesium carbonate would be 1 μmol per 1 mol of the dihydroxycompounds to prepare a mixture. The obtained polycarbonate resin had anintrinsic viscosity of 0.29 and a pencil hardness of H.

Reference Example 3-1 Preparation of PC(a3-1) (BPC Homopolymer, MeltMethod)

To 37.60 kg (about 147 mol) of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) as the material dihydroxy compound and 32.20 kg(about 150 mol) of diphenyl carbonate (DPC), an aqueous solution ofcesium carbonate was added so that cesium carbonate would be 2 μmol per1 mol of the dihydroxy compound to prepare a mixture. The mixture wascharged into a first reactor having an internal volume of 200 L equippedwith a stirring machine, a heat medium jacket, a vacuum pump and areflux condenser.

Then, an operation of reducing the pressure in the first reactor to 1.33kPa (10 Torr) and then recovering it to the atmospheric pressure withnitrogen was repeatedly carried out five times, and the interior in thefirst reactor was replaced with nitrogen. After replacement withnitrogen, a heat medium at a temperature of 230° C. was passed throughthe heat medium jacket to gradually increase the internal temperature inthe first reactor to dissolve the mixture. Then, the stirring machinewas rotated at 300 rpm, and the temperature in the heat medium jacketwas controlled to maintain the internal temperature of the first reactorat 220° C. Then, while phenol formed as a by-product by anoligomerization reaction of BPC and DPC carried out in the interior ofthe first reactor was distilled off, the pressure in the first reactorwas reduced from 101.3 kPa (760 Torr) to 13.3 kPa (100 Torr) over aperiod of 40 minutes.

Then, the pressure in the first reactor was maintained at 13.3 kPa, andwhile phenol was further distilled off, an ester exchange reaction wascarried out for 80 minutes.

Then, the pressure in the system was recovered to 101.3 kPa by theabsolute pressure with nitrogen, and then the pressure was elevated to0.2 MPa by the gauge pressure, and the oligomer in the first reactor waspumped to a second reactor by means of a transfer pipe preliminarilyheated to at least 200° C. The second reactor had an internal volume of200 L, was provided with a stirring machine, a heat medium jacket, avacuum pump and a reflux condenser, and had the internal pressure andthe internal temperature controlled to be the atmospheric pressure and240° C.

Then, the oligomer pumped to the second reactor was stirred at 38 rpm,the internal temperature was raised by the heat medium jacket, and thepressure in the second reactor was reduced from 101.3 kPa to 13.3 kPa bythe absolute pressure over a period of 40 minutes. Then, the temperatureraising was continued, and the internal pressure was reduced from 13.3kPa to 399 Pa (3 Torr) by the absolute pressure further over a period of40 minutes, and the distilled phenol was removed out of the system.Further, the temperature raising was continued, and after the absolutepressure in the second reactor reached 70 Pa (about 0.5 Torr), apressure of 70 Pa was maintained, and a polycondensation reaction wascarried out. The final internal temperature in the second reactor was285° C. When the stirring machine of the second reactor achieved apreliminarily determined stirring power, the polycondensation reactionwas completed.

Then, the pressure in the second reactor was recovered to 101.3 kPa bythe absolute pressure with nitrogen, and then the pressure was elevatedto 0.2 MPa by the gauge pressure, and the polycarbonate resin waswithdrawn from the bottom of the second reactor in the form of strands,which were pelletized by using a rotary cutter while cooling in a watertank. The viscosity average molecular weight of the obtainedpolycarbonate resin was 17,200.

The polycarbonate resin was evaluated in accordance with the aboveitems. The results are shown in Table 3-1.

Reference Example 3-2 Preparation of PC(a3-2) (BPC Homopolymer, MeltMethod)

The same operation as in Reference Example 3-1 was carried out exceptthat the preliminarily determined stirring power of the stirring machineof the second reactor was changed. The obtained polycarbonate resin hada viscosity average molecular weight of 18,500.

The results of evaluation in the same manner as in Reference Example 3-1are shown in Table 3-1.

Reference Example 3-3 Preparation of PC(a3-3) (BPC Homopolymer, MeltMethod)

The same operation as in Reference Example 3-1 was carried out exceptthat the preliminarily determined stirring power of the stirring machineof the second reactor was changed. The obtained polycarbonate resin hada viscosity average molecular weight of 30,300.

The results of evaluation in the same manner as in Reference Example 3-1are shown in Table 3-1.

Reference Example 3-4 Preparation of PC(a3-4) (Bis-OCZ Homopolymer, MeltMethod)

The same operation as in Reference Example 3-1 was carried out exceptthat 43.48 kg of Bis-OCZ (manufactured by HONSHU CHEMICAL INDUSTRY CO.,LTD.) was used instead of BPC as the material dihydroxy compound, andthe aqueous solution of cesium carbonate was added so that cesiumcarbonate would be 5 μmol per 1 mol of the dihydroxy compound. Theobtained polycarbonate resin had a viscosity average molecular weight of10,200.

The results of evaluation in the same manner as in Reference Example 3-1are shown in Table 3-1.

Reference Example 3-5 Preparation of PC(a3-5) (BPC/BPA (30/70 wt %)Copolymer, Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 3-1 except that 10.05 kg of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) and 23.45 kg of BPA (manufactured by MitsubishiChemical Corporation) were used instead of BPC as the material dihydroxycompounds. The obtained polycarbonate resin had a viscosity averagemolecular weight of 25,200.

The results of evaluation in the same manner as in Reference Example 3-1are shown in Table 3-1.

Reference Example 3-6 Preparation of PC(a3-6) (BPC/BPA (10/90 wt %)Copolymer, Melt Method)

A polycarbonate resin was obtained in the same manner as in ReferenceExample 3-1 except that 3.35 kg of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) and 30.15 kg of BPA (manufactured by MitsubishiChemical Corporation) were used as the material dihydroxy compounds. Theobtained polycarbonate resin had a viscosity average molecular weight of24,700.

The results of evaluation in the same manner as in Reference Example 3-1are shown in Table 3-1.

(2) Polycarbonate Resin (b) Reference Example 7 Preparation of PC(b1)(BPA/BPC Copolymer)

A polycarbonate resin (PC(b1)) was obtained in the same manner as inReference Example 2 except that 30.5 kg of(2,2-bis(4-hydroxyphenyl)propane (BPA) (manufactured by MitsubishiChemical Corporation) and 3.4 kg of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) were used instead of BPC as the material dihydroxycompounds. The viscosity average molecular weight, the glass transitiontemperature (Tg) and the pencil hardness are as shown in Table 1.

Reference Example 8 Preparation of PC(b2) (BPA/BPC Copolymer)

A polycarbonate resin (PC(b2)) was obtained in the same manner as inReference Example 2 except that 24.2 kg of BPA (manufactured byMitsubishi Chemical Corporation) and 10.4 kg of BPC (manufactured byHONSHU CHEMICAL INDUSTRY CO., LTD.) were used instead of BPC as thematerial dihydroxy compounds. The viscosity average molecular weight,the glass transition temperature (Tg) and the pencil hardness are asshown in Table 1.

Reference Example 9 PC(b3)

As PC(b3), a commercially available polycarbonate resin constituted onlyby structural units derived from BPA, formed by the melt method, wasused. It had a viscosity average molecular weight of 20,600 and a meltviscosity of 9,010 poise. Further, it had an intrinsic viscosity of 0.47and a pencil hardness of 2B.

Reference Example 2-11 PC(b2-1) (M7027J (BPA Homopolymer) Manufacturedby Mitsubishi Engineering-Plastics Corporation)

As PC(b2-1), a commercially available polycarbonate resin constitutedonly by structural units derived from BPA, formed by the melt method,was used. It had a viscosity average molecular weight of 25,600 and amelt viscosity of 22,120 poise. Further, it had an intrinsic viscosityof 0.56 and a pencil hardness of 2B.

Reference Example 2-12 PC(b2-2) (BPA/BPC Copolymer (Melt Method))

A polycarbonate resin was obtained in the same manner as in ReferenceExample 2-7 except that 27.4 kg of BPA (manufactured by MitsubishiChemical Corporation) and 6.8 kg of BPC (manufactured by HONSHU CHEMICALINDUSTRY CO., LTD.) were used instead of BPC as the material dihydroxycompounds. It had an intrinsic viscosity of 0.48 and a pencil hardnessof HB.

Reference Example 3-7 PC(b3-1) (BPA Homopolymer, Melt Method)

As PC(b3-1), a commercially available polycarbonate resin (M7022Jmanufactured by Mitsubishi Engineering-Plastics Corporation) constitutedonly by structural units derived from BPA, formed by the melt method,was used. The viscosity average molecular weight of PC(b3-1) was 20,000.

The results of evaluation in the same manner as in Reference Example 3-1are shown in Table 3-1.

The glass transition point (Tg), the viscosity average molecular weight(Mv) and the pencil hardness of the polycarbonate resins (a) and (b)used as the materials of the polycarbonate resin compositions inExamples and Comparative Examples are shown in Table 1.

TABLE 1 PC resin Blend ratio (wt %) (abbreviated of dihydroxy Pencilname) compound Tg (° C.) Mv hardness PC(a1) BPC(100) ≦100 1,900 PC(a2)BPC(100) 101 6,700 PC(a3) BPC(100) 119 18,500 2H PC(a4) BPC(100) 12233,000 2H PC(a5) Bis-OCZ(100) 132 10,200 3H PC(a6) Bis-OCZ(100) 13849,900 3H PC(b1) BPA/BPC 144 21,700 B (90/10) PC(b2) BPA/BPC 138 20,300F (70/30) PC(b3) BPA(100) 145 20,600 2B

Examples 1 to 9 and Comparative Examples 1 to 5

Using the above polycarbonate resins, by a twin screw extruder (LABOTEX30HSS-32) manufactured by Japan Steel Works, Ltd. having one vent port,the respective polycarbonate resin compositions were prepared.

Example 1

As the polycarbonate resin (a) and the polycarbonate resin (b), PC(a2)and PC(b3) in a ratio as identified in Table 2 were melt-kneaded in theabove twin screw extruder, extruded from the outlet of the twin screwextruder in the form of strands, solidified by cooling with water, andpelletized by a rotary cutter to obtain a polycarbonate resincomposition. On that occasion, the barrel temperature of the twin screwextruder was 280° C., and the polycarbonate resin temperature at theoutlet of the twin screw extruder was 300° C. At the time ofmelt-kneading, the vent port of the twin screw extruder was connected toa vacuum pump, and the pressure at the vent port was controlled to be500 Pa.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the melt viscosity and the Charpy impact strength, in accordance withmethods as described in the above evaluation items. The results areshown in Table 2 together with the amount of the polycarbonate resinused.

Examples 2 to 9

Polycarbonate resin compositions were obtained in the same manner as inExample 1 except that two types of polycarbonate resins as identified inTable 2 were employed.

The polycarbonate resin compositions were subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the melt viscosity and the Charpy impact strength, in accordance withmethods as described in the above evaluation items. The results areshown in Table 2 together with the amount of the polycarbonate resinsused.

Further, the polycarbonate resin compositions in Examples 3 to 6 weremolded into extruded articles (sheets) by the above method, which weresubjected to evaluation with respect to the pencil hardness and theyellowness index (YI). The results are shown in Table 2.

Example 10

As the polycarbonate resin (a) and the polycarbonate resin (b), pelletsof PC(a3) and pellets of PC(b3) were dry-blended in a ratio asidentified in Table 2 to obtain a polycarbonate resin composition.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the melt viscosity and the Charpyimpact strength in accordance with methods as described in the aboveevaluation items. The results are shown in Table 2 together with theamount of the polycarbonate resin used.

Comparative Examples 1 to 2

Polycarbonate resin compositions in Comparative Examples 1 and 2 wereobtained in the same manner as in Example 1 except that two types ofpolycarbonate resins as identified in Table 2 were employed.

The polycarbonate resin compositions were subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the melt viscosity and the Charpy impact strength in accordance withmethods as described in the above evaluation items. The results areshown in Table 2 together with the amount of the polycarbonate resinsused.

Further, the polycarbonate resin composition in Comparative Example 1was molded into an extruded article (sheet) by the above method, whichwas subjected to evaluation with respect to the pencil hardness and theyellowness index (YI). The results are shown in Table 2.

Comparative Examples 3 to 5

The surface hardness, the glass transition temperature (Tg), the meltviscosity and the Charpy impact strength of PC(b2) in ComparativeExample 3, PC(b1) in Comparative Example 4 and PC(b3) in ComparativeExample 5 by themselves were evaluated. The results are shown in Table2.

Further, the polycarbonate resin compositions in Comparative Examples 3to 5 were molded into extruded articles (sheets) by the above method,which were subjected to evaluation with respect to the pencil hardnessand the yellowness index (YI). The results are shown in Table 2.

TABLE 2 Ex. PC resin 1 2 3 4 5 6 7 8 PC(a) PC(a1) — — — — — — — — partsby weight PC(a2) 10 20 — — — — — — PC(a3) — — 10 20 30 — — — PC(a4) — —— — — 10 20 30 PC(a5) — — — — — — — — PC(a6) — — — — — — — — PC(b)PC(b1) — — — — — — — — parts by weight PC(b2) — — — — — — — — PC(b3) 9080 90 80 70 90 80 70 Mv (a)/Mv (b) 0.335 0.335 0.925 0.925 0.925 1.651.65 1.65 Pencil hardness of PC composition HB F F F H HB F F Differencein pencil hardness between 2 3 3 3 4 2 3 3 PC composition and PC(b) Tg(° C.) 138 134 142 139 136 143 140 138 Melt viscosity (poise) 5,7473,506 7,846 6,915 5,978 9,417 10,340 11,140 Charpy impact strength(kJ/m²) 11 9 14 11 8 12 11 10 YI (—) 2.5 2.3 2.3 2.5 2.8 2.8 2.8 3.3Pencil hardness of PC sheet — — F F H F — — Thickness (μm) of PC sheet —— 240 240 240 240 — — YI (—) of PC sheet — — 0.86 0.86 0.87 0.87 — — Ex.Comp. Ex. PC resin 9 10 1 2 3 4 5 PC(a) PC(a1) — — 20 — — — — parts byweight PC(a2) — — — — — — — PC(a3) — 30 — — — — — PC(a4) — — — — — — —PC(a5) 10 — — — — — — PC(a6) — — — 20 — — — PC(b) PC(b1) — — — — — 100 —parts by weight PC(b2) — — — — — — 100 PC(b3) 90 70 80 80 100 — — Mv(a)/Mv (b) 0.51 0.925 0.095 2.495 — — — Pencil hardness of PCcomposition HB H F F 2B B F Difference in pencil hardness between 2 4 33 0 0 0 PC composition and PC(b) Tg (° C.) 144 — 122 143 145 144 138Melt viscosity (poise) 7,930 6,080 1,920 17,570 9,010 8,830 9,210 Charpyimpact strength (kJ/m²) 12 8 5 11 72 14 8 YI (—) 1.9 2.7 3.5 3.8 1.9 2.42.9 Pencil hardness of PC sheet — — B — B HB F Thickness (μm) of PCsheet — — 240 — 240 240 240 YI (—) of PC sheet — — 0.93 — 0.88 0.95 0.99

By comparison between Examples 1, 3 and 6 and Comparative Example 4, asthe blend ratio of the dihydroxy compound is the same, the content ofstructural units derived from each dihydroxy compound is estimated to bethe same. Nevertheless, it is found that the pencil hardness asspecified by ISO 15184 in Examples 1, 3 and 6 is higher than the pencilhardness in Comparative Example 4. A difference in the pencil hardnesseven with the same amount of structural units contained is also shown inExamples 5 and 10 and Comparative Example 5. Further, in ComparativeExamples 1 and 2, polycarbonate resin compositions by combination ofpolycarbonate resins having no specific glass transition temperature areemployed, and in Comparative Example 1, it is found that the Charpyimpact strength is deteriorated, and the glass transition temperature(Tg) is very low. Further, in Comparative Example 2, it is found thatalthough there are no problems in the pencil hardness and the Charpyimpact strength, the melt viscosity is very high, the fluidity is notfavorable, and the moldability is poor.

Example 2-1

A polycarbonate resin composition was obtained by pelletizing in thesame manner as in Example 1 except that as the polycarbonate resin (a)and the polycarbonate resin (b), PC(a1) and PC(b1) were melt-kneaded ina ratio as identified in Table 2-1.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the yellowness index (YI), the glasstransition temperature (Tg), the melting viscosity and the Charpy impactstrength in accordance with methods as described in the above evaluationitems. The results are shown in Table 2-1.

Examples 2-2 to 2-7

Polycarbonate resin compositions in Examples 2-2 to 2-7 were obtained inthe same manner as in Example 1 except that two types of polycarbonateresins as identified in Table 2-1 were employed.

The polycarbonate resin compositions are subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the yellowness index (YI), the melt viscosity and the Charpy impactstrength in accordance with methods as described in the above evaluationitems. The results are shown in Table 2-1.

Further, the polycarbonate resin compositions in Examples 2-6 and 2-7were molded into extruded articles (sheets) by the above method, whichwere subjected to evaluation with respect to the pencil hardness and theyellowness index (YI). The results are shown in Table 2-1.

Example 2-8

As the polycarbonate resin (a) and the polycarbonate resin (b), pelletsof PC(a2-6) and pellets of PC(b3) were dry-blended in a ratio asidentified in Table 2-1 to obtain a polycarbonate resin composition inExample 2-8.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the yellowness index (YI) and theCharpy impact strength in accordance with methods as described in theabove evaluation items. The results are shown in Table 2-1 together withthe amount of the polycarbonate resin used.

Further, the polycarbonate resin composition was molded into an extrudedarticle (sheet) by the above method, which was subjected to evaluationwith respect to the pencil hardness and the yellowness index (YI). Theresults are shown in Table 2-1.

Comparative Example 2-1

A polycarbonate resin composition in Comparative Example 2-1 wasobtained in the same manner as in Example 2-1 except that PC(b3) and theBPC monomer as identified in Table 2-1 were employed.

The polycarbonate resin composition was subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the yellowness index (YI), the melt viscosity and the Charpy impactstrength in accordance with methods as described in the above evaluationitems. The results are shown in Table 2-1.

Comparative Examples 2-2 to 2-5 and 2-8

Polycarbonate resin compositions in Comparative Examples 2-2 to 2-5 and2-8 were obtained in the same manner as in Example 2-1 except that twotypes of polycarbonate resins as identified in Table 2-1 were employed.

The polycarbonate resin compositions were subjected to evaluation withrespect to the surface hardness, the glass transition temperature (Tg),the yellowness index (YI), the melt viscosity and the Charpy impactstrength. The results are shown in Table 2-1.

Further, the polycarbonate resin compositions in Comparative Examples2-2 and 2-8 were molded into extruded articles (sheets) by the abovemethod, which were subjected to evaluation with respect to the pencilhardness and the yellowness index (YI). The results are shown in Table2-1.

Comparative Examples 2-6, 2-7 and 2-9

The surface hardness, the glass transition temperature (Tg), theyellowness index (YI), the melt viscosity and the Charpy impact strengthof PC(b3) in Comparative Example 2-6, PC(b2-1) in Comparative Example2-7 and PC(b2-2) in Comparative Example 2-9 by themselves wereevaluated. The results are shown in Table 2-1.

Further, the polycarbonate resin composition in Comparative Example 2-6was molded into an extruded article (sheet) by the above method, whichwas subjected to evaluation with respect to the pencil hardness and theyellowness index (YI). The results are shown in Table 2-1.

TABLE 2-1 Polycarbonate resin (a) Polycarbonate resin (b) Glass Glasstransition Blending transition Blending temp. amount Pencil temp. amountPencil Type (° C.) (wt %) [η]a hardness Type (° C.) (wt %) [η]b hardnessEx. 2-1 PC(a2-1) A1* 132 20 0.23 3H PC(b3) A6* 145 80 0.47 2B Ex. 2-2PC(a2-2) A2* 125 20 0.07 3H PC(b3) A6* 145 80 0.47 2B Ex. 2-3 PC(a2-3)A2* 138 20 0.26 3H PC(b3) A6* 145 80 0.47 2B Ex. 2-4 PC(a2-4) A3* <10020 0.06 2H PC(b3) A6* 145 80 0.47 2B Ex. 2-5 PC(a2-5) A4* 110 20 0.25 2HPC(b3) A6* 145 80 0.47 2B Ex. 2-6 PC(a2-6) A3* 101 20 0.18 2H PC(b3) A6*145 80 0.47 2B Ex. 2-7 PC(a2-6) A3* 101 20 0.18 2H PC(b2-1) A6* 147 800.56 2B Ex. 2-8 PC(a2-6) A3* 101 20 0.18 2H PC(b3) A6* 145 80 0.47 2BEx. 2-9 PC(a2-10) A5* 161 30 0.29 H PC(b3) A6* 145 70 0.47 2BPolycarbonate resin composition Polycarbonate sheet Yellow- Glass CharpyComparison Yellow- Melt ness transition impact of pencil ness Monomerunit (wt %) [η]a/ Pencil viscosity index temp. strength hardness PencilThickness index BPC BisOCZ BPA [η]b hardness (poise) (—) (° C.) (kJ/m²)with PC(b) hardness (μm) (—) Ex. 2-1 — 20 80 0.5 F 6,811 2.3 143 9 Threeranks — — — up (2B→F) Ex. 2-2 — 20 80 0.15 F 2,546 1.9 126 6 Three ranks— — — up (2B→F) Ex. 2-3 — 20 80 0.56 F 6,801 2.0 142 9 Three ranks — — —up (2B→F) Ex. 2-4 20 — 80 0.14 HB 5,013 2.4 128 8 Two ranks up — — —(2B→HB) Ex. 2-5 20 — 80 0.53 F 5,161 3.2 138 8 Three ranks — — — up(2B→F) Ex. 2-6 20 — 80 0.39 F 3,506 2.3 134 9 Three ranks F 240 0.85 up(2B→F) Ex. 2-7 20 — 80 0.26 F 7,320 2.3 142 11 Three ranks HB 240 0.85up (2B→F) Ex. 2-8 20 — 80 0.39 F 3,457 2.2 — 9 Three ranks F 240 0.85 up(2B→F) Ex. 2-9 15 85 0.20 F — 2.5 149 9 Three ranks — — — up (2B→F)Polycarbonate resin (a) Polycarbonate resin (b) Glass Glass transitionBlending transition Blending temp. amount Pencil temp. amount PencilType (° C.) (wt %) [η]a hardness Type (° C.) (wt %) [η]b hardness Comp.— A7* —   0.1 0.01 — PC(b3) A6* 145 99.9 0.47 2B Ex. 2-1 Comp. PC(a2-7)A3* 122 10 0.69 2H PC(b3) A6* 145 90 0.47 2B Ex. 2-2 Comp. PC(a2-7) A3*122 20 0.69 2H PC(b3) A6* 145 80 0.47 2B Ex. 2-3 Comp. PC(a2-8) A4* 12520 0.97 2H PC(b3) A6* 145 80 0.47 2B Ex. 2-4 Comp. PC(a2-9) A1* 138 200.98 3H PC(b3) A6* 145 80 0.47 2B Ex. 2-5 Comp. — — — — — — PC(b3) A6*145 100 0.47 2B Ex. 2-6 Comp. — — — — — — PC(b2-1) A6* 147 100 0.56 2BEx. 2-7 Comp. PC(a2-7) A3* 122 20 0.69 2H PC(b2-1) A6* 147 80 0.56 2BEx. 2-8 Comp. — — — — — — PC(b2-2) A8* 142 100 0.48 HB Ex. 2-9Polycarbonate resin composition Polycarbonate sheet Yellow- Glass CharpyComparison Yellow- Melt ness transition impact of pencil ness Monomerunit (wt %) [η]a/ Pencil viscosity index temp. strength hardness PencilThickness index BPC BisOCZ BPA [η]b hardness (poise) (—) (° C.) (kJ/m²)with PC(b) hardness (μm) (—) Comp. 0.1 — 99.9 0.01 2B 8,900 1.9 145 72No change — — — Ex. 2-1 Comp. 10 — 90 1.48 HB 9,417 2.8 143 12 Two ranksF 240 0.86 Ex. 2-2 up (2B→HB) Comp. 20 — 80 1.48 F 10,340 3.0 140 11Three ranks — — — Ex. 2-3 up (2B→F) Comp. 20 — 80 2.08 F 14,260 1.9 14110 Three ranks — — — Ex. 2-4 up (2B→F) Comp. — 20 80 2.08 F 17,570 3.8146 11 Three ranks — — — Ex. 2-5 up (2B→F) Comp. — — 100 — 2B 9,010 1.9145 72 No change B 240 0.88 Ex. 2-6 Comp. — — 100 — 2B 19,200 2.0 146 75No change — — — Ex. 2-7 Comp. 20 — 80 1.23 F 18,830 2.7 143 14 Threeranks F 240 0.86 Ex. 2-8 up (2B→F) Comp. 20 — 80 — HB — 2.7 142 6 — — —— Ex. 2-9 A1*: Bis-OCZ homopolymer (interfacial method) A2*: Bis-OCZhomopolymer (melt method) A3*: BPC homopolymer (melt method) A4*: BPChomopolymer (interfacial method) A5*: CDOBC/BPA (50/50 wt %) copolymerA6*: BPA homopolymer (melt method) A7*: BPC monomer A8*: BPA/BPCcopolymer (melt method)

By comparison between Examples 2-1 to 2-3 and Comparative Example 2-6,it is found that in Examples 2-1 to 2-3, the pencil hardness asspecified by ISO 15184 is higher by three ranks than in ComparativeExample 2-6, the melt viscosity is lower than in Comparative Example2-6, and the moldability is improved. By comparison between Example 2-4and Comparative Example 2-1, it is found that in Example 2-4, the pencilhardness as specific by ISO 15184 is high, and the melt viscosity islow. In Examples 2-5 to 2-7 and Comparative Example 2-9, as the blendratio of the dihydroxy compound is the same, the content of structuralunits derived from each dihydroxy compound is estimated to be the same.Nevertheless, it is found that the pencil hardness as specific by ISO15184 in Examples 2-5 to 2-7 is higher than the pencil hardness inComparative Example 2-9, the melt viscosity in Examples 2-5 to 2-7 islower than the melt viscosity in Comparative Example 2-9, and themoldability is improved. Further, by comparison between Example 2-7 andComparative Example 2-8, it is found that although there is nodifference in the pencil hardness, in Example 2-7, the melt viscosity islow, and the yellowness index (YI) is favorable.

The blending amount (wt %) of the dihydroxy compound of thepolycarbonate resins (a) and (b) used as materials of the polycarbonateresin compositions in Examples and Comparative Examples, the viscosityaverage molecular weight (Mv) and the pencil hardness are shown in Table3-1.

TABLE 3-1 Blend ratio (wt %) of Intrinsic Abbreviated dihydroxyviscosity Pencil name compound Mv (η) hardness Ref. Ex. 3-1 BPC BPC(100) 17200 0.4 2H homopolymer (a3-1) Ref. Ex. 3-2 BPC BPC (100) 185000.43 2H homopolymer (a3-2) Ref. Ex. 3-3 BPC BPC (100) 30300 0.69 2Hhomopolymer (a3-3) Ref. Ex. 3-4 BisOC-Z BisOC-Z(100) 10200 0.23 3Hhomopolymer (a3-4) Ref. Ex. 3-5 BPC/BPA BPC/BPA 25200 0.55 F copolymer(30/70) (a3-5) Ref. Ex. 3-6 BPC/BPA BPC/BPA 24700 0.55 B copolymer(10/90) (a3-6) Ref. Ex. 3-7 BPA BPA (100) 20000 0.46 2B homopolymer(b3-1) Ref. Ex. 9 BPA BPA (100) 20600 0.47 2B homopolymer (b3) Ref. Ex.2-11 BPA BPA (100) 25600 0.56 2B homopolymer (b2-1)

Example 3-1

As the polycarbonate resin (a) and the polycarbonate resin (b), PC(a3-1)and PC(b3-1) in a ratio as identified in Table 3-2 were melt-kneaded ina twin screw extruder (LABOTEX 30HSS-32) manufactured by Japan SteelWorks, Ltd. having one vent port, extruded from the outlet of the twinscrew extruder in the form of strands, solidified by cooling with water,and pelletized by a rotary cutter to obtain a molded article ofpolycarbonate resin. On that occasion, the barrel temperature was 280°C., and the polycarbonate resin temperature at the outlet of the twinscrew extruder was 300° C. At the time of melt-kneading, the vent portof the twin screw extruder was connected to a vacuum pump, and thepressure at the vent port was controlled to be 500 Pa.

This molded article of polycarbonate resin was subjected to evaluationwith respect to the surface hardness, the Charpy impact strength, theyellowness index (YI), the content ([S]) of structural units (a) on thesurface of the molded article of polycarbonate resin and the content([T]) of structural units (a) in the entire molded article ofpolycarbonate resin in accordance with methods as disclosed in theabove-described evaluation items.

The results are shown in Table 3-2. In Example 3-1, the structural units(a) are structural units derived from BPC.

Examples 3-2 to 3-4

Molded articles of polycarbonate resin in Examples 3-2 to 3-4 wereobtained in the same manner as in Example 3-1 except that two types ofpolycarbonate resins as identified in Table 3-2 were employed. Further,the results of evaluation in the same manner as in Example 3-1 are shownin Table 3-2. In Examples 3-2 and 3-3, the structural units (a) arestructural units derived from BPC, and in Example 3-4, the structuralunits (a) are structural units derived from Bis-OCZ.

Comparative Examples 3-1 to 3-4

Molded articles of polycarbonate resin in Comparative Examples 1 to 4were obtained in the same manner as in Example 1 except that two typesof polycarbonate resins as identified in Table 3-2 were employed.Further, the results of evaluation in the same manner as in Example 3-1are shown in Table 3-2. In Comparative Examples 3-1 and 3-4, thestructural units (a) are structural units derived from BPC.

Comparative Examples 3-5 to 3-8

Molded articles of polycarbonate resin in Comparative Examples 3-5 to3-8 were obtained by using PC(a3-2) in Comparative Example 3-5, PC(b3)in Comparative Example 3-6, PC(a3-5) in Comparative Example 3-7 andPC(a3-6) in Comparative Example 3-8 by themselves as shown in Table 3-2.Further, the results of evaluation in the same manner as in Example 3-1are shown in Table 3-2. In Comparative Examples 3-5, 3-7 and 3-8, thestructural units (a) are structural units derived from BPC, and inComparative Example 3-6, the structural units (a) are structural unitsderived from BPA.

TABLE 3-2 Molded article of polycarbonate resin Content of Content ofStructural units Pencil Polycarbonate resin (a) Polycarbonate resin (b)structural units structural units (a) content ratio hardness on Blend-Blend- (a) on the (a) in the between surface the surface Charpy ing ingStruc- surface of entire molded layer/the entire of molded impact amountamount tural molded article article [S]/[T] article strength Type wt %Type wt % units (a) wt % wt % — — kJ/m² Ex. 3-1 BPC 20 BPA 80 BPC 23 201.15 F 11 homopolymer homopolymer (a3-1) (b3-1) Ex. 3-2 BPC 10 BPA 90BPC 11 10 1.1 F 14 homopolymer homopolymer (a3-2) (b3) Ex. 3-3 BPC 10BPA 90 BPC 10.5 10 1.05 HB 17 homopolymer homopolymer (a3-2) (b2-1) Ex.3-4 BisOC-Z 20 BPA 10 BisOC-Z 22 20 1.1 F 9 homopolymer homopolymer(a3-4) (b1) Comp. BPC 50 BPA 50 BPC 49 50 0.98 H 7 Ex. 3-1 homopolymerhomopolymer (a3-2) (b1) Comp. BPC 20 BPA 80 BPC 20 20 1.0 HB 11 Ex. 3-2homopolymer homopolymer (a3-3) (b4-1) Comp. BPC 10 BPA 90 BPC 10 10 1.0HB 14 Ex. 3-3 homopolymer homopolymer (a3-3) (b1) Comp. BPC 10 BPA 80BPC 10 10 1.0 B 10 Ex. 3-4 homopolymer homopolymer (a3-3) (b2-1) Comp.BPC 100 — — BPC 100 100 1.0 2H 6 Ex. 3-5 homopolymer (a3-2) Comp. — —BPA 100  — 100 100 1.0 2B 72 Ex. 3-6 homopolymer (b3) Comp. BPA/BPC70/30 — — BPC 30 30 1.0 F 8 Ex. 3-7 copolymer (a3-5) Comp. BPA/BPC 90/10— — BPC 10 10 1.0 B 14 Ex. 3-8 copolymer (a3-6)

By comparison between Example 3-1 and Comparative Example 3-2, althoughthe content ([T]) of the structural units (a) (structural units derivedfrom BPC) in the entire molded article of polycarbonate resin is thesame, it is found that in Example 3-1, the content ([S]) of thestructure units (a) on the surface of the molded article ofpolycarbonate resin is high, and the pencil hardness as specified by ISO15184 in Example 3-1 is higher than the pencil hardness in ComparativeExample 3-2.

Likewise, by comparison between Example 3-2 and Comparative Examples 3-3and 3-8, although the content ([T]) of the structural units (a)(structural units derived from BPC) in the entire molded article ofpolycarbonate resin is the same, it is found that in Example 3-2, thecontent ([S]) of the structural units (a) (structural units derived fromBPC) on the surface of the molded article of polycarbonate resin ishigh, and the pencil hardness as specified by ISO 15184 is high, ascompared with Comparative Examples 3-3 and 3-8.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to obtain apolycarbonate resin composition and a molded article, which have aparticularly excellent surface hardness and which have excellent heatresistance, moldability (fluidity), color, impact resistance, flameretardancy and the like, by a simple method. This molded article isapplicable particularly to applications for which the surface hardnessis required, such as electric/electronic equipment fields such ascellular phones and personal computers, automobile fields such asheadlamp lenses and windows for vehicles, and building material fieldssuch as illumination and exterior.

This application is a continuation of PCT Application No.PCT/JP2011/058336, filed on Mar. 31, 2011, which is based upon andclaims the benefit of priority from Japanese Patent Application No.2010-083181 filed on Mar. 31, 2010, Japanese Patent Application No.2010-262055 filed on Nov. 25, 2010, Japanese Patent Application No.2010-262056 filed on Nov. 25, 2010, Japanese Patent Application No.2011-018525 filed on Jan. 31, 2011, Japanese Patent Application No.2011-018526 filed on Jan. 31, 2011, Japanese Patent Application No.2011-047877 filed on Mar. 4, 2011 and Japanese Patent Application No.2011-076450 filed on Mar. 30, 2011. The contents of those applicationsare incorporated herein by reference in its entirety.

1. A polycarbonate resin composition comprising at least a polycarbonateresin (a) and a polycarbonate resin (b) having structural unitsdifferent from the polycarbonate resin (a), which satisfies thefollowing requirements: (i) the pencil hardness of the polycarbonateresin (a) as specified by ISO 15184 is higher than the pencil hardnessof the polycarbonate resin (b) as specified by ISO 15184; (ii) the glasstransition point Tg(a) of the polycarbonate resin (a) and the glasstransition point Tg(b) of the polycarbonate resin (b) satisfy therelation of the following (Formula 1):Tg(b)−45° C.<(a)<Tg(b)−10° C.  (Formula 1) and (iii) the pencil hardnessof the polycarbonate resin composition as specified by ISO 15184 ishigher by at least two ranks than the pencil hardness of thepolycarbonate resin (b) as specified by ISO
 15184. 2. A polycarbonateresin composition comprising at least a polycarbonate resin (a) and apolycarbonate resin (b) having structural units different from thepolycarbonate resin (a), which satisfies the following requirements: (i)the pencil hardness of the polycarbonate resin (a) as specified by ISO15184 is higher than the pencil hardness of the polycarbonate resin (b)as specified by ISO 15184; and (ii) the ratio of the intrinsic viscosity[η](a) of the polycarbonate resin (a) to the intrinsic viscosity [η](b)of the polycarbonate resin (b), [η](a)/[η](b), is at least 0.1 and atmost 0.65.
 3. The polycarbonate resin composition according to claim 1,wherein the ratio of the viscosity average molecular weight Mv(a) of thepolycarbonate resin (a) to the viscosity average molecular weight Mv(b)of the polycarbonate resin (b), Mv(a)/Mv(b), is at least 0.1 and at most2.0.
 4. The polycarbonate resin composition according to claim 1,wherein the weight ratio of the polycarbonate resin (a) to thepolycarbonate resin (b) in the polycarbonate resin composition is withina range of from 1:99 to 45:55.
 5. The polycarbonate resin compositionaccording to claim 1, wherein the pencil hardness of the polycarbonateresin (a) as specified by ISO 15184 is at least F.
 6. The polycarbonateresin composition according to claim 1, wherein the pencil hardness ofthe polycarbonate resin composition as specified by ISO 15184 is atleast HB.
 7. The polycarbonate resin composition according to claim 1,wherein the above Tg(a) and Tg(b) satisfy the relation of the following(Formula 2):Tg(b)−30° C.<Tg(a)<Tg(b)−15° C.  (Formula 2)
 8. The polycarbonate resincomposition according to claim 1, wherein the polycarbonate resin (a) isa polycarbonate resin having at least structural units derived from acompound represented by the following formula (1):

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.
 9. The polycarbonate resin composition according to claim 1,wherein the polycarbonate resin (a) is a polycarbonate resin having atleast structural units derived from at least one compound selected fromthe group consisting of the following formulae (1a) to (1c):


10. The polycarbonate resin composition according to claim 1, whereinthe polycarbonate resin (b) is a polycarbonate resin having mainlystructural units derived from a compound represented by the followingformula (2):


11. The polycarbonate resin composition according to claim 1, which hasa yellowness index (YI) of at most 4.0.
 12. The polycarbonate resincomposition according to claim 1, which further contains a flameretardant.
 13. A method for producing the polycarbonate resincomposition as defined in claim 1, which comprises melt-kneading thepolycarbonate resin (a) and the polycarbonate resin (b).
 14. A methodfor producing the polycarbonate resin composition as defined in claim 1,which comprises dry-blending the polycarbonate resin (a) and thepolycarbonate resin (b).
 15. An injection-molded article, which isobtained by injection-molding the polycarbonate resin composition asdefined in claim
 1. 16. An extruded article, which is obtained byextruding the polycarbonate resin composition as defined in claim
 1. 17.The extruded article according to claim 16, which is a sheet or a film.18. A molded article of polycarbonate resin, comprising thepolycarbonate resin composition as defined in claim 8, wherein the ratioof the content [S] of the structural units (a) derived from a compoundrepresented by the following formula (1) on the surface of the moldedarticle of polycarbonate resin to the content [T] in the entire moldedarticle of polycarbonate resin ([S]/[T]) is higher than 1.00 and at most2.00:

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.
 19. The molded article of polycarbonate resin according to claim18, which is an injection-molded article.
 20. The molded article ofpolycarbonate resin according to claim 18, wherein the ratio of thecontent [S] of the structural units (a) on the surface of the moldedarticle of polycarbonate resin to the content [T] in the entire moldedarticle of polycarbonate resin ([S]/[T]) is at least 1.01 and at most1.50.
 21. The molded article of polycarbonate resin according to claim18, wherein the pencil hardness on the surface of the molded article ofpolycarbonate resin as specified by ISO 15184 is at least HB.
 22. Themolded article of polycarbonate resin according to claim 18, wherein thestructural units (a) are structural units derived from at least onecompound selected from the group consisting of the following formulae(1a) to (1c):


23. The molded article of polycarbonate resin according to claim 18,wherein the polycarbonate resin (b) is a polycarbonate resin havingmainly structural units (b) derived from a compound represented by thefollowing formula (2):


24. The molded article of polycarbonate resin according to claim 18,which comprises at least a polycarbonate resin (a) having structuralunits (a) derived from a compound represented by the formula (1) and apolycarbonate resin (b) having structural units (b) different from thestructural units (a) and having a structure different from thepolycarbonate resin (a).
 25. The molded article of polycarbonate resinaccording to claim 18, wherein the pencil hardness of the polycarbonateresin (a) as specified by ISO 15184 is higher than the pencil hardnessof the polycarbonate resin (b) as specified by ISO
 15184. 26. The moldedarticle of polycarbonate resin according to claim 18, wherein the pencilhardness of the polycarbonate resin (a) as specified by ISO 15184 is atleast F.
 27. The molded article of polycarbonate resin according toclaim 18, wherein the viscosity average molecular weight of thepolycarbonate resin (a) is higher than the viscosity average molecularweight of the polycarbonate resin (b).
 28. A method for producing themolded article of polycarbonate resin as defined in claim 18, comprisingat least a polycarbonate resin (a) having structural units (a) derivedfrom a compound represented by the following formula (1) and apolycarbonate resin (b) having structural units (b) different from thestructural units (a), which comprises melt-kneading or dry-blending thepolycarbonate resin (a) and the polycarbonate resin (b), followed bymolding, wherein the viscosity average molecular weight of thepolycarbonate resin (a) is higher than the viscosity average molecularweight of the polycarbonate resin (b):

wherein each of R¹ and R² which are independent of each other, is asubstituted or non-substituted C₁₋₂₀ alkyl group or a substituted ornon-substituted aryl group, each of R³ and R⁴ which are independent ofeach other, is a hydrogen atom, a substituted or non-substituted C₁₋₂₀alkyl group or a substituted or non-substituted aryl group, and X is asingle bond, a carbonyl group, a substituted or non-substitutedalkylidene group, an oxidized or non-oxidized sulfur atom, or an oxygenatom.
 29. The method for producing the molded article of polycarbonateresin according to claim 28, wherein the structural units (a) arestructural units derived from at least one compound selected from thegroup consisting of the following formulae (1a) to (1c):


30. The method for producing the molded article of polycarbonate resinaccording to claim 28, wherein the structural units (b) are mainlystructural units derived from a compound of the following formula (2):


31. The method for producing the molded article of polycarbonate resinaccording to claim 28, wherein the molding is injection-molding.